Interestingly, the computer that connects with windows security is using a ms online account running windows on MacBootCamp on a Macbook. The one that fails is a regular windows machine & an ms online account.
I have a user with two windows machines, both using the same online account to login. One of them works normally, as expected with windows security, the other exhibits the behavior being discussed in this thread.
Try again, folks, Microsoft account isn't the problem.
We are not using RUServer. These are simple win10 machines. Out of 13 identically configured workstations, 5 end users had to be set to single password auth. With ALL of those cases, my workstations at home get the windows auth window.
With all of these users, the Viewer would attempt to connect, and on the 2nd or 3rd attempt, the user/pass/domain dialog appears and then disappears. After 5 failed attempts the viewer fails and reports access denied, bad credentials.
This occurs when auth is set to "auto" or "windows security".
Initially it appeared these were win10home users, but i've seen at least two using win10pro. Most likely these users have not updated their home machines, because that's how people are, but i don't know that for a fact.
I'm sorry i don't have any further details to assist.
i will try, but these are users remoting in, i've only helped them via slack, and i don't have access to those workstations. So far about 1/2 of our staff has had this happen. I tried on hosts running both 6.10.9 and 6.10.10, but the result was the same, even after upgrading the older host.