Microsoft has released a fix to address the regression introduced with September 2020 CU for SharePoint Server 2019.
If you did not install September CU you can skip installing KB 4484505 and use the fix below instead. If you already installed KB 4484505 you can install KB 4461512 on top of it to resolve the issue.
KB article and download link for the fix can be found here:
- KB 4461512: September 21, 2020, update for SharePoint Server 2019
- Fix download Link: September 21, 2020, update for SharePoint Server 2019
Important: You have to install KB 4484504 together with this update if you did not install it earlier, otherwise, some features won’t work.
As with all SharePoint fixes you have to run the SharePoint configuration wizard after applying the fix.