Odd XQD card problem

Sorry if this post is in the wrong place but hopefully somebody will be able to help.
I have a Nikon D500 and a Z6, both of which use XQD cards. Up until a few days ago my XQD card reader worked faultlessly with my iMac and I was able to load RAW images into Lightroom CC from either camera.
Suddenly, the XQD card in my D500 was unrecognised by my iMac and so no images could be transferred from it (the SD card was fine). What is odd is that the same card, when inserted into my Z6, shows images on the LCD screen and photos taken on the Z6 using that card can be viewed on the D500 screen when the card is reinserted into it. Reformatting the cared in either the D500 or Z6 makes no difference.
My XQD card reader works with my MacBook and reads my original XZ6 XQD card but again doesn't recognise the D500 card. Which seems to indicate the card reader is working OK?
Rather stupidly I tried a brand new XQD card in the D500 and now that card is not recognised by my iMac, but again seems to work in the Z6 BUT IS UNREADABLE AGAIN BY THE IMAC EVEN AFTER REFORMATTING IN THE Z6!
My D500 has the latest firmware (C1.3) and I have even reinstalled it just to be sure.
I am totally confused and now have 2 XQD cards that work in both cameras but not with my card reader.
I am grateful for any advice.
thanks,
Hadrian
I have a Nikon D500 and a Z6, both of which use XQD cards. Up until a few days ago my XQD card reader worked faultlessly with my iMac and I was able to load RAW images into Lightroom CC from either camera.
Suddenly, the XQD card in my D500 was unrecognised by my iMac and so no images could be transferred from it (the SD card was fine). What is odd is that the same card, when inserted into my Z6, shows images on the LCD screen and photos taken on the Z6 using that card can be viewed on the D500 screen when the card is reinserted into it. Reformatting the cared in either the D500 or Z6 makes no difference.
My XQD card reader works with my MacBook and reads my original XZ6 XQD card but again doesn't recognise the D500 card. Which seems to indicate the card reader is working OK?
Rather stupidly I tried a brand new XQD card in the D500 and now that card is not recognised by my iMac, but again seems to work in the Z6 BUT IS UNREADABLE AGAIN BY THE IMAC EVEN AFTER REFORMATTING IN THE Z6!
My D500 has the latest firmware (C1.3) and I have even reinstalled it just to be sure.
I am totally confused and now have 2 XQD cards that work in both cameras but not with my card reader.
I am grateful for any advice.
thanks,
Hadrian

Some clarification?
Are you saying that both cards perform correctly when you use them in your Z6 followed by a download via your card reader?
In other words, everything's as it should be?
They both work in your D500, in that they record your images but the card is then not recognised by your card reader?
Are you saying that both cards perform correctly when you use them in your Z6 followed by a download via your card reader?
In other words, everything's as it should be?
They both work in your D500, in that they record your images but the card is then not recognised by your card reader?

Both cards work correctly in either camera - they can be formatted and read in-camera and when swapped over between cameras they each work in-camera.
However, once either card has been inserted into the D500 and an image recorded, neither are recognised by the card reader, even after reformatting in the Z6.
I'm suspecting my D500 is somehow corrupting the cards, but if so, why can the Z6 read and write to them?
However, once either card has been inserted into the D500 and an image recorded, neither are recognised by the card reader, even after reformatting in the Z6.
I'm suspecting my D500 is somehow corrupting the cards, but if so, why can the Z6 read and write to them?

Quote:I'm suspecting my D500 is somehow corrupting the cards
It does look that way.
Quote:neither are recognised by the card reader, even after reformatting in the Z6.
There's a lot of nonsense bandied about re. the formatting of memory cards and I won't claim to be an expert but I'm not sure that formatting cards in one camera prepares them for use in another.
Having said that, and at a bit of a tangent, I've got a pile of old SD cards that have seen service in and been formatted in, various DSLRs over the years and they all still work. In fact, I know someone who invariably formats her cards on her computer, something the so-called experts cringe at yet she never seems to have a problem.
You haven't mentioned it but can you download the images directly (via Usb.) from your D500?

Reading some other complaints on this issue on the web it seems that the Lexar XQDs are giving a number of problems whereas the Sony ones seem to work without problem. A number of folk have reported formatting the card on the computer using the Mac utility gets it working again, but this does not necessarily last on the Lexar.

Yes I would probably agree with you there as Amazon, whilst they have some very good points, do tend to sell some stuff which is not 100%. So if you can download from the D500 by USB I would suggest that you use that method to download your images from both cameras. I always have done and have never experienced any problems at all. Mine, however, are not XQD! But I don't think that will actually make any difference.

When you format a card in camera - a file is added to the card noting the camera model.
This is why it can be best to format in camera, especially if you have more than 1 card and more than 1 camera body.
My system with Lightroom is to create a folder name on my hard drive, to insert the card in a a Sony card reader - at which stage Lightroom recognises the camera model as the download source - direct the download to the folder I want it to go into - and import.
Lightroom (and probably a lot of other software) adds the camera model, lens model, shutter speed, aperture and the time you took the photo (more accurate than 1 second)
Try formatting a card in camera - and see if everything works as it should. If not maybe you need a new card reader
This is why it can be best to format in camera, especially if you have more than 1 card and more than 1 camera body.
My system with Lightroom is to create a folder name on my hard drive, to insert the card in a a Sony card reader - at which stage Lightroom recognises the camera model as the download source - direct the download to the folder I want it to go into - and import.
Lightroom (and probably a lot of other software) adds the camera model, lens model, shutter speed, aperture and the time you took the photo (more accurate than 1 second)
Try formatting a card in camera - and see if everything works as it should. If not maybe you need a new card reader

PROBLEM SOLVED!!!!
Thanks for all your advice folks. I discovered that my cheap Amazon (Rocketek) XQD card reader is so flimsy that the two XQD cards I used in my D500 didn't make perfect electrical contact in the reader and that by applying pressure on the card it's suddenly recognised by my Mac again.
Moral of the story is you get what you pay for so I'm ordering a Sony card reader now. Thanks again for your advice.
Thanks for all your advice folks. I discovered that my cheap Amazon (Rocketek) XQD card reader is so flimsy that the two XQD cards I used in my D500 didn't make perfect electrical contact in the reader and that by applying pressure on the card it's suddenly recognised by my Mac again.
Moral of the story is you get what you pay for so I'm ordering a Sony card reader now. Thanks again for your advice.