Yeah I'm getting this too. It is incredibly annoying and it leads to me getting nuked to death on my wizard as soon as most fights with ranged or quick enemies begins, considering equipping him in heavier armor and a medium shield but it sucks having to do that because my formations are being ignored for combat encounters. Rearranging the portraits at the bottom helps, but that gets constantly reset to a the MC being placed first and having to rearrange that and/or fix formations afterwards is a pain. Seems to happen when you enter combat from the map when entering a site too. How my formation is supposed to look vs how it looks after entering combat from the map https://imgur.com/a/0mG9duf