So here a short answer to myself. If anybody runs into this problem.
I contacted the adobe support. (chat)
After going back and forth, I was told to "rebuild the sync databank"
You can find this in the preferences under "Lightroom sync" and you need to hold down the
"alt" key to see and execute the rebuild.
I had to do this twice and it was hard to stay patient but after waiting for some hours
I could see a progress and feedback in the apps too.
In the end all the collections where synced.
I am curious what the problem was, but I am happy that all the data was back again.
You need a fast internet connection (mine is 50mb/s up).
I hope this helps
Peter
I speak german, english,spanish specs: iMac iMac.27" 17.1 Intel Core i7 processor:4 GHz Ram :32 GB Premiere CC 14.0.1 German Version. Handle ohne zu tun; ohne Anstrengung arbeiten. Stell dir das Kleine gross vor und das Wenige als Viel. Beschäftige mit dem Schwierigen, solange es noch einfach ist. Erfülle die große Aufgabe durch viele kleine Taten. Act without doing; work without effort. Think of the small as large and the few as many. Confront the difficult while it is still easy; accomplish the great task by a series of small acts.
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