It reads the SD card or USB folder names but does no recognize any of my gcode files.
Not sure of your exact scenario, but you must use the SD card reader on the TFT or other display, not the card reader on the main control board. And it expects “.gcode” as the extension.
It is an issue with windows 10. If you change the extension from “GCODE” to “gcode” Windows thinks you really didn’t intend to change it and it DOESN’T CHANGE it. If you change it to anything else “xyz” or whatever THEN change it to “gcode” that works.
In Windows, file names are case insensitive, so “.gcode” is the same as “.GCODE” is the same as “.gCoDe.” I’m not sure if Marlin treats the names as case sensitive or insensitive. I’m not home, so I cannot check. I would hope that it is insensitive.