I have found out why this happens! I had in Viewer selected 'Tabbed View', as I cleared this, the Remote machine opens as expected in full screen. When I select tabbed viewing again the error comes back.
Tabbed view is toggled in the Viewer under Tools/Options/Remote Screen
I have exactly the same problem as Rene. I have tried from to different PC's and connecting to different PC's - allways start in a little window upper left. As Rene tells, you can click on the little icon in the Processline, that will open full screen. Pressing F12 will alternatively move you through the different settings. This must be a program bug.
When using Agent on the remote machine, I mark Restart after reboot. But the Agent ius never starting again, and the remote user has to start Agent before I can connect again. How can I make the Agent restart after reboot? When updating Windows it is necessary to restart, so yhis is really needed.