If it’s not absolutely vital for some reason to have cloud saving, then simply switch to local saves permanently.
Then just back them up on an external drive of some kind regularly. Just nagivate to My Documents\My Games\Grim Dawn\save, right click on Save and then choose Send to copy it wherever you want it to go to.
I sometimes link this thread several times a day to posts about this sort of thing because cloud saving seems to be getting more and more unreliable every time Steam updates it’s system.