I think the skipped turns comes from the "shared" initiative slots.....
Not necessarily.
I just had a fight and paid special attention to this behavior. Gale's turn was skipped at least once.
1. It's Lae'Zel's turn. She moves and gets downed by an opportunity attack.
2. Redcaps turn. It runs around and casts their rage ability.
3. Gale's turn. According to the images on the top. He does nothing and is skipped.
4. Instead it's immediately the turn of a different Redcap. That Redcap knocks Gale out.
By this point did my main character attack four times/took four turns. Gale should have taken at least three turns, but acted only once.
(He did make two opportunity attacks during the fight and acted normally on the first turn of combat.)