PRS-T1 not mounting on M2 Mac

My Sony PRS-T1 is no longer mounting on my M2 Mac. It mounted fine when I first bought the Mac.

I have tried three different cables to no avail.

I can turn on the content server in Calibre and download books that way but that is a real pain and I have to know what I want to download because it is so slow to load the pages.

Any ideas?