hi love the game best buy so far this year but there seems to be a extreme bug that will/has halted playing any further what happens is this one first seeing a sectopod ic an shoot it not a problem it looses some health but when its the aliens turn its health regenerates and after that it cant be killed all hits go to 1% hit and it doesn't loose health it becomes invincible this bug is a game killer cause well cant continue on cause cant kill it
First thing to check would be whether there are any drones nearby - their main focus is to heal sectopods or cyberdisks. Hopefully you aren't playing ironman so can try reloading. If it still happens, I guess make a note of roughly where it is on the map, have your whole squad ready to fire, and try to do the 30+ points of damage in one turn when it can be damaged to kill it outright. Failling that load a save from before that mission, hopefully not losing too much progress, and continue from there. I've not seen or heard of this on PC, so hopefully this is just a one off glitch and not a common bug.