project manager unknown error

win 10

premiere pro 2020

project on external hd, enough disk space

tried everything i found in the forum, also unchecking preview files and audio conform files.

nothing worked. this is really annoying as it seems  to be a new bug.

luckily i have another device (win10) with the premiere pro cc 2019 and there the project manager, with the exact same project on the exact same external drive with the exact same destination folder worked just fine.

please fix this @adobe.