Google translation: "Lightroom Classic 11.3.1 no longer syncs metadata. Also, the program keeps crashing with an "unexpected error". When is the bug fix coming? It can't stay like this. Lightroom Classic has never been as bad as it is today."
I agree that LR 11.3 and 11.3.1 have been the buggiest releases in a very long time.
There are several known bugs in LR 11.3 and 11.3.1 with the display of metadata in the Metadata panel, including a bug with Auto Sync:
You can work around that bug by setting the option Catalog Settings > Metadata > Automatically Write Changes Into XMP.
If that doesn't help, or you are using something other than "Auto Sync" to copy metadata, I suggest you roll back to LR 11.2. LR generally releases every 8 weeks, so we'd expect to see 11.4 released in the next week or two, with hopefully many bug fixes.
If you still experience these problems with LR 11.4, or rolling back to 11.2 doesn't help, then make a new post with much more detail, as recommended here: