Once my troops are wounded (lets say a Party - 4 units), if I keep them outside of my settlements to heal, they eventually heal at full capacity over a long period of time. But if I store them inside a settlement, the party will often go from 4 to 3 or 2 or 1 unit (plus it will also take the same amount of time to heal). This is very disturbing since they have accumulated a lot of experience (high hit points).