The RTH issue I was having turned out to be a "Setup Problem" in the DJI app. A switch regarding RTH had been turned off . Everything is back to normal. Nothing to do with the LItchi App.
Here my correspondence with DJI:
Dear Lance,
Appreciate your comment regarding the third party Litchi app. For your information I discovered that when using the DJI Go4 app, one of the switches regarding RTH had been switched off. Switching back on, things return to normal and the RTH is working fine. Note that in the our discussions/texts regarding the RTH problem, we didn’t review any of the settings (I maybe should have asked the right questions). Before assuming that everything were as it should be, I re-tested the Litchi App and flew a few programed missions (with RTH checked to apply at the end of mission) everything worked fine and the drone landed right on its mark.
Point is the Litchi app was not the issue, it was my incorrect setup in the DJI Go 4 App, which was overlooked on my part.
I might mention the it would be nice if DJI were to offer the waypoint setup feature such as Litchi, then your customer would be tempted to resort to third party apps!
Cheers