Here is a problem i never had on linux but i started getting on windows.
Some games say they are unable to sync (seemingly random), when i start a game the save does seem to have downloaded, but i cant sync it as it is right now, even doing so manually keeps throwing the same error
I had this same problem for months and had a hard time finding anything on it. The thing that finally fixed it for me was to disable IPv6 on my network adapter. After that everything syncs fine.