Quick update: I’m definitely seeing some hangs as well. Most clear up in an hour or two, but folders that hang seem to get stuck indefinitely on “scanning”. Restarting might temporarily resolve the problem (not enough has been synced yet for me to do a definitive test).
Digging into the errors in out.txt reveals exactly the same API error as described here is occuring:
Going to keep on keeping on to see if I can get a full sync.