Are you editing a big module that someone else created? I ask because you mention a GKC to switch off Moved, which implies you’re not using the default menu bar button to do so that can be configured in the properties of a Map window. So someone who worked on the module before you may have set up a trigger than spots the GKC for turning moved off and is manually turning trails back on.
The reason they’d be doing that is because, as you say, those two traits DO interact in weird and frustrating ways. Doing the Moved reset for a piece also switches its Trails off, and so module designers who want Trails to be either on or off for all pieces (rather than the players needing to switch them on and off for every piece individually, which is pretty cumbersome for the player) have to maintain a way to keep separate track of whether Trails are “supposed to be” on for a piece, and then switch them back on when the other function (the clear move function) does it’s unwanted turning-off of them.
Anyway that’s possibly the kind of thing you’re encountering. I can confirm that the Moved / Trails interaction is weird and often very very frustrating. What I wouldn’t do for a way to directly set the Trails & Moved flags for a piece (rather than only indirectly “toggling” them), and a way to read the Trails flag.
Nope, my module from the ground up. The idea is that trails are on by default, because players don’t tend to touch menu settings and they are useful for PBEM, and the Moved state is used to reset trails at the end of each turn. For solo players or players who just don’t like trails, I would like to be able to let them permanently switch off trails if they wish to do so, through my setup window, without requiring use of a menu option they may not know exists.
I haven’t figured out a way to do this, despite all the possibilities teased by the Vassal UI, as nothing seems to work as advertised.
FWIW, I have absolutely no use for Mark as Moved in this module other than the fact that it is apparently required for trails.