The word from on high is it'll get fixed/patched in due course, till then dig them in manually every turn.
"In PBEM games, that is unfortunately true, and is an unintended consequence of the way the we zero out the movement points on all units as the game closes after the end of the turn. In hotseat, or player vs PO games, that is not the case. I'll ask Ralph to look at the code and see if we can work around that, and restore the feature to PBEM games. Thanks for catching that!"
rest of the thread is here
http://www.xtreme-gamer.com/forums/opera...ent-2.html
Just my impression but I think if you miss a turn or whatever it appears a unit that has been stationary for a while digs in faster when you do dig it in.
Hotkey "D" VERY useful now (digs in and moves to next unit)