CPAP machine not recording data on SD card??

I have a Phillips Respironics CPAP machine. For some reason, it stopped recording data on the SD card on 4/30. That is the last date looking at the files in Explorer - it's also the last date for data in my analysis program. There is plenty of room left on the card. I also tried an empty card, same result. Any ideas. Thanks

Have you tried formatting the SD card on your computer, inserting it into the CPAP machine, and then looking at it back on the computer?

If the CPAP is accessing the card, it will write files to the card consisting of ID information about it and the last session you had. If the machine does not do that, its off the the DME for repairs / replacement.

I guess it's off for repairs - I did try a brand new, freshly formatted card as well.