I am so sick of this.
After having installed a bunch of windows updates I am not able to show my remote desktop connection in full screen mode on my secondary monitor anymore. I have been doing this for years and now it suddenly doesn't work anymore. The time I always loose after windows updates to solve problems like this is unbelievable. Maybe I should charge MS for it...
Anyway, what I did so far was opening an RDC, then dragging the window to the secondary monitor, closing it and opening it again after changing the resolution settings to full screen. This would open the new RDC window in full screen mode on the secondary monitor. For whatever reason now the new window is always being opened on the primary monitor.
And please don't tell me this is a feature.