Thanks @Cyril Dellenbach
I've sorted this now and it's all working.
in case anyone else has the same issue. Essentially, I had folders in the program folder and the document folder for Substance Painter 3d set up for the (non Steam) version 2022 as symlinks or windows junctions, in order to save space on my C drive. This was wreaking havoc with the Steam installation approach, as well as with Nvidia Omniverse connector installation. I also had to figure out how to uninstall connectors from Omnive
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