Issues with catalog backup in Photoshop Elements

Hi, I'm using Photoshop Elements 2021 with the latest update. When ever I want now to backup my catalog (either full back up or just the meta data) I get a pop up that the back is getting prepared. So far so good, but then nothing happens. In Windows Task Manager I can see that s tatus of Photoshop Elements is no response. 

I have around 16 300 pictures in this library. 

Also it seems that the creation of the miniatures fail. The message in the lower left hand corner says quite a while now 3 of 10000 created, without any progress. 

Best Sven