I was having issues with my anycubic mega pro SD card disconnecting midprint, or not showing files. Forums helped me get files to show sometimes once I shortened the file names but still needed to wiggle the card. Electronics contact cleaner and checking the ribbon cable didn't do it either
Turns out a little bit of pressure of the right part of the SD reader's metal casing did just the trick
Had trouble locating the spot. Using ZIP tie to shim under the printer plate. Hopefully this isn't needed in all cases, give it a shot!
Hope this saves you the $12 of buying a new ribbon cable SD reader
The author hasn't provided the model origin yet.