Hello, I'm so sorry to necro this thread, but I am experiencing the same troubles, and I'd like to see if I can offer any additional information about this.
I own DE on Steam and Switch (digital download). After I log in with my Steam credentials on Switch, everything works just as expected. I have access to all my PC saves with no problems playing, loading, saving, or syncing new saves to the cloud and my PC.
I have tried most of the suggestions above, including a new idea that occurred to me. I had the game installed on my Switch SD Card, so I moved it into the internal storage to see if that would change anything. It did not, unfortunately.
I have also experienced this issue both docked (wired via ethernet) and handheld (wireless home network).
I'm on Switch firmware 10.0.4, NA region.
Again, sorry for the necro, it just appears that this issue hasn't been resolved. My steam password is long and randomized by a password manager, so I would rather not have to enter the password every single time I want to play in bed.
Last edited by ItsSteve; 20/06/20 04:45 PM.