That was what i meant, the selection window closes but nothing in the tool window changes (all decrypt options are still greyed out, the window still shows a "please select directory" message etc). And I did check, the files are not yet decrypted.
Thanks a lot, but I guess this is not the place for me to try to solve this, i'll see if i can find something on the tool's github.
Edit: In case anyone has similar problems: Seems like it was an issue with my java version, just installed a different one.