I have a similar issue with XRDP going to a blank screen. The only thing I could find (a few months ago) was that in 18.04 for unknown reasons XRDP doesn't work if the user is already logged on ...
So I just had a thought this morning... has anybody tried using xRDP as a gateway to VNC consoles of KVM guests? [globals] bitmap_cache=yes bitmap_compression=yes port=3389 crypt_level=low ...