We use TV on our LAN to remote control a stack of MacMinis, one per MacOS, for support purposes - we test software on each releease of OSX. This used to work OK, but recently I am finding that any connection attempt to a Mac which is not already logged in will display the login screen, but I cannot interact with that screen at all - can't click on the user avatar, can't enter a password. Walking over the the stack of Macs and using the KVM switch to find the right one, then "waking it it" by clicking on the keyboard then allows password entry via TV. However, I then have to disconnect TV and re-connect, because the desktop is not drawn.
This occurs on El Capitan, Sierra, High Sierra and Mojave. Teamviewer version 13.2.14327