I have the red exclamation mark on my Sync button. I don't have a "Conflicting Changes" notebook, but I have pinpointed at least one note that isn't in sync. The log has an "unexpected problem server-side" error repeatedly. I see this message in my logs going back for a month or so, but I don't see any details that would help me understand what the issue is. I'll attach the log (had to truncate it due to size).
I'm subscribed, but I did not see a way to contact support.