I've tried revoking the connection through the app and then re-adding it. It says that it's trying to create an account rather than just adding the sync to the one that already exists. Do I need to revoke it across all my devices? As I also have a tablet that's connected? It basically just tries to create a new sync account with my Google info when one already exists. I'd be fine with deleting my old account on the web site if that's an option too.
Oddly enough it re-syncs fine on my tablet (galaxy tab s 8.4 with marshmallow rom) but doesn't on my marshmallow stock Nexus 6.