Since 19.18 update I can't sync anymore Spotify or other music apps

As title says, I'm no more able to sync any music provider since last update.

Tried to uninstall and reinstall, deleted every playlist I had on my watch but the synchronization is very slow and gets stuck at ~5%.

Many feedbacks on Spotify's Connect IQ page are reporting my same problem but I can't find anything on here or any solution. 

Is anyone on my same boat?