So I'm playing the latest version of Bronze Age and I essentially wiped out as Shontu tribe -- which gave me three Shontu regions. Now, they don't supply the Humitte armies that make up most of my land, so the only reasonable way was to abandon them and immediately resettle them with Humittes.
Unfortunately, abandoning them caused my units to just sit there and not do anything until I saved and reloaded -- and the same problem occurred when I abandoned-and-resettled a second region (the first had a settlement, the second had a walled village).
On a side note, if you take all of a Shontu force's land but don't wipe out all their units, the game thinks they're still active, despite them having no land and 0 population (it doesn't even recognize the people wandering with their oxen!)
EDIT: Speaking of bugs, there's no way to promote citizens or nobles into leadership. As a result, my dynasty has nine adults, four children/babies, and eighteen regions... which means half the nation has to go without a governor.