Did I get it right that you try to sync from your laptop to your desktop machine? - Guido
I have exactly the same problem on my iMac. I did a CC update yesterday and since then the little synch icon next to collections that were synching are gone and no matter what I try : sign out of CC, restart, Delete All Data, etc. Nothing is bringing them back. The synch status shows 'waiting to connect', but it has always shown that and a known LR issue.
I'm thinking it's a new bug introduced in the update.
Could you please send me a LR Desktop diagnostig log - best as a private message with a downloadable dropbox link.
You can trigger the log via LR Desktop preferences -> Lightroom Mobile and when you hold down the alt key you will notice a generate diagnostic log button
You should have the link. Sent in private messsage!
Did you get the file OK? I haven't heard anything.