Application wrotes to screen using ? commands

SYS(602 , 1 )
MODIFY WINDOW screen FONT 'Arial',14
_Screen.Themes = .F.
hide menu _msysmenu
ACTIVATE SCREEN
clear

do while .t.
clear
  ?'1 Option1'
  ?'2 Option 2'
  ?'.  Exit'
  
  wait 'Select ' to valik
clear
...

If running under RDP after switching to local desktop and back to RDP meu disappears. Whole screen is blank.

How to fix this so that menu is visible after switching back to application ? I tried SYS(602 , 1 ) and SYS(602 , 0 ) but this
does not fix blank screen.