I have found a problem, at the start of dogeball, sometimes carla wont throw her ball has anyone found this problem themself?

As far as I know, this is just a problem in the game that you kind of have to deal with. It happened to me a few times before, and I think your best option is to just restart gym.

yeah, I have to agree with what SugarFreeLemon says, from what I understand in my many runs is that it is truly just random, and it is what it is, your best bet is to restart gym which doesn't take too much time