Teamviewer ID not generating on one user when 2 users logged on simultaneously

I have 2 users logging on to the same PC simultaneously via N-computing. Teamviewer 14 starts at startup in both computers, but generated ID & password only on the user-2. It only displays a (-) dash in the ID & password fields of the primary user (myself). Moreover when I enter my user+password in the  Computers and Contacts on the primary user, the option of Sign In stays dehighlighted.

I've tried everything, including downgrading to TV-13. If I keep the N-computing user switched off and restart the PC, then teamviewer works perfectly on the primary machine, including Computers and Contacts. But as soon as I switch on the other user, the ID & password disappear from the 1st user and gets displayed on the other.

Teamviewer Error.png

I don't need teamviewer on the 2nd user and would be happy to use it a single user (if that solves my issue). But I don't see any option to allow / disallow the application user-wise.