Prior to the Android 10 update I remember the phone asking each time I plugged it in what USB mode I wanted to use. Doesn't do that any more & all the USB options are greyed out. Anyway to get back the option to use USB for file transfer?
Mine always ask even with Android 10.
Check the usb cable. I had the same issue and it was a cable failure
Thanks for the suggestion, I tried a different cable and like you said the options for file transfer reappeared.