I’ve never experienced this before so thought it might be new to 0.9.0 or later.
I just fought Lagon on empowered mono on an FG using MA. The MA very shortly into the fight stopped attacking so I resummoned him and he started attacking again. but stopped very shortly after that. I had to keep resummoning him to get any use out of him at all for the fight. He was fine during the middle phase of destroying the tentacles but both the initial and final phases with Lagon is where this occurred.
I know Lagon is being seriously looked at and revamped but wanted to make sure this issue was known while looking into the whole mess that is Lagon.
EDIT: Just noticed this is happening with FW also, except that only some of the weapons go inactive. I’m not sure why some would and others not but that’s the behavior I just had with 2 Lagon runs back-to-back.