Sync stuck - Please help

I recently created a new catalog to attempt to resolve some sync issues. After a few days of downloading (29k images), my new catalog is stuck with 415 downloading and 25 pending (upload number varies). I tried to rebuild the sync data with the same result.

My computer is a 2018 Macbook Pro 2.6Ghz I7 with 32g Ram. I'm running LrC  13.0.2 and latest version of Lightroom. 

What is my next course of action to resolve this issue?

Thanks. 

[moved from bugs to discussions according to the community rules - Mod.]