For Britain I remember there was a rule (in the boardgame) that requires a certain number of corps to be kept in England, but I'm not sure the rule is also in the PC game.
I think the best way (for me) is to debug your saved game and check if there's something wrong in the frontiers garrisoning checks. But I see you removed the saved games.
Understood, unfortunately there are some modded files in use that might cause a crash if the save is plugged into Stock so decided against uploading them all. I have four corps and Third Army HQ in Britain, a continuous line of units (although there is at least one province with a single corps only) along the Western Front and the Italian Africa unit in Libya as garrison.
Was hoping that there was some undocumented condition that I am failing to meet rather than seeing a bug. Am testing some mods with this campaign but none that should effect garrison requirements.
Thanks for replying.