I have windows 10 and we recently upgraded to v12 from v8. Teamviewer is always set to start on startup and is visible in the System Tray. I pin the Icon to Taskbar and whenever I click it I get an error popup telling me another instance is already running. Not sure how I can just bring the computers and contact window. Basically the "Show Team viewer" command to bring th eapp to front from the taskbar icon.
It is really annoying
This is happening to me now too. Never happened to me before this last windows update and reboot. It's super annoying.