Lightroom not working anymore - cannot add new collections

Since I have changed the setting in my catalogue to write automatically metadata changes into the XMP-files, my catalogue is not working anymore as it should. I cannot add new collections or change the names of collections. The only thing I can do, is deleting collections. Shut down of LRC takes a long time.

I guess there are activities running in the background but I cannot see those ore stopp it.

I have alredy reset the preferences but still not working. What can I do?