I have both Tumbleweed (with all the latest updates and a 5.9.1 kernel) and Leap 15.2 virtual machines. Both auto boot into an LXDE session but also have Plasma installed and I use XRDP (version 0.9.14-104.2 from the X11 repository). I use the standard windows RDP client with same settings to access both systems.
On the Leap system (which starts with an auto login to a LXDE session on the main console) I can RDP into either LXDE or Plasma desktop environments by editing /etc/xrdp/startwm.sh and everything works as expected.
On the Tumbleweed system (also logsin to an console LXDE session) I can start a remote session for LXDE with no problem but if I try and start a Plasma session I go through the lightbulb splash screen but then the screen/window goes blank and nothing seems to work. Quite bizarly when in this state, if I log out on the LXDE session on the main console and relogin to a plasma session I get a blank screen on the main console and a plasma session now appears on the RDP window! Nothing significant appears if a check the status of xrdp.service or xrdp-sesman.service and the output is the same as on the Leap system.
Anyone got any ideas?
PS Will probably try a fresh install to see if the behaviour is repeatable.