LRC left syncing 1000 new photos overnight and 0 uploaded

I'm trying to fundamentally understand the issue with LRC. 

I had a synced collection that appears in LR cloud. I added 1000 new photos to it last night from an engagement shoot and left my computer on overnight to sync. LRC is set to prevent sleep while synching, and windows sleep settings were set to not sleep. 

This morning the computer was still on - did not go to sleep. However, upon checking before leaving for a trip where I planned to cull/edit/send out samples from the shoot, I have 0 new photos uploaded to my lr cloud and available on my mobile devices.

What gives?