[Help] Permalinks are not working

Hello, not so long time ago I have encountered an issue with my osclass, whenever a link with attributes is being opened it returns an error 404. E.g. https://website/user/items?itemType=active
while https://website/user/items is working just fine.
I would assume it is due to permalinks not being functional, since whenever I try to go to the corresponding section of my admin panel (Pemalinks) it returns HTTP Error 500.
If you have any suggestions on how to fix it, I much appreciate your feedback, thank you in advance.

https://forums.osclasspoint.com/osclass/404-error-after-osclass-update-(v8-3-0)/

The issue is, whenever I go to click on Permalinks in settings I get Error 500. Everything else in admin panel works fine

You must enable error log to see what is behind that error 500.
Reuploading osclass files may help.