Publish Service to Hard Drive exits with error message

I updated LrC from 11.4.1 to 12.1 on Windows 11 and my existing publish services won't finish successful anymore. I have several different publish services containing different (smart) collections, all with local hard drive as the destination. After pressing the Publish button a Export Results window states the following message: An unknown error occurred. This photo was not rendered. (1)

Even though the image is unexpectedly exported to the local hard drive, the images remain in the section "New Photos to Publish" - expected to be moved to "Published Photos".