This issue have a workaround.mE commented
Found a solution!
It is Apple new Samba (SMB2) protocol that creates trouble. The specifics are described at this German blog post: https://tsia.me/einer-dieser-manchmal-bugs/
Long story short: instead of smb:// use afp:// (you can also try with cifs://, if afp doesn't work/) to connect to your network shares. Be sure to also recreate all the folder aliases that point to a network location (NAS etc.).mE commented
The same problem. It tends to work after I restart the computer, but after certain amount of time, (a few minutes, a few hours) the account icon just gets the red stroke and bam, nothing could be done.