This is most likely a bug issue. I have had the problem in a ranked game at least 10 times over the years. Sometimes it does seem suspiciously well timed for some players advantage, but if someone is hacking to disconnect other players from the game, I have never heard confirmation on here. The disconnect bug, the reset to start position bug, and the troop placement bug all seem to be tied together and often happen together in my experience.
A variety I have never seen discussed on here but have seen myself in game is the reset to start position that lasts an entire turn while you are locked out with the troop placement bug and then it reverts to the live current position. No idea if all the players see that or just the player experiencing the troop placement bug.
This sometimes happens if you restart the app and rejoin the game to try to escape the troop placement bug. That is what I have seen lately.
It has been longer since I have seen an actual reset to start positions where the game plays out from there. Usually most all the players quit not knowing that you can play the game out from there. Even seen one reset to start positions twice, after that everyone except me was a bot. I have been able to theorize that a lot of these bugs seem to be triggered by the timing of disconnects by players (maybe the host disconnecting is especially important). Hopefully all this will be made irrelevant when SMG completes the network overhaul.
Also think I once described one on here where I selected a cap at least 6 times in at least 3 different positions, but that all happened in quick succession so that might be more related to the disconnect bug. I don’t remember if I ended up with the troop placement bug or if I went on to win that one.