Garmin 500 won't activate and fly other legs in flight plan

I used to be able to switch my P3D Maule M7 Garmin 500 to advance to any other leg in my flight plan, but no more. Steps I used are:

FPL>activate cursor>Scroll down to a fix for leg after current leg>menu>activate leg using enter button.

This worked great until recently when I tried to set up a flight plan on my Electronic Flight Bag. Now I cannot activate the selected leg, even with EFB not running.

Tried updating P3D v5 to a newer minor version (content and client to 5.0.31.35253) but that failed to fix the problem.

Help with suggested repair is really appreciated.

Thanks, Gary