I literally laughed out loud when you said that it was caused by Atton dying.
The thing is, I don't really use Atton in the game, because I prefer Bao-Dur. So, when it came time to fight the Twi'Lek sisters, I didn't really have all the right items for Atton. I literally had to run around throwing adhesive grenades at them, and then plasma grenades whilst they were stuck.
I managed to defeat the sisters, but Atton only had like 3 hp remaining by the end of the fight. I'm guessing he must've been poisoned or had something happen to him just after his battle.
Also, I remember him dying during the cutscene where he's talking to the rest of the crew on the landing pad. As in, he died in the middle of the cutscene. But when I reloaded, he seemed fine.
Personally, I think the game doesn't optimise Atton that well when levelling him up. Although I can say the same for many people.
Actually, maybe that could be something you guys could change in one of the TSLRC updates.
Like, how Mandalore gets strength as his recommended attribute, even though the game gives him a mostly-ranged set up for his feats...