That seems to be unrelated. I started a new game, cheated in a LRB, gave it to Trask, and dropped a save before first combat: Trask gets his extra attacks.
Loaded that save: Trask does not get extra attacks.
Using the repeater version. I have a save where it does seem to work reliably on Mission but I seem to be able to break it by cycling her out of and back into the party or zone transition.
I've been trying this with Mission but it appears that the mechanisms involved in making the extra attacks happen do not reliably persist across loading saves, loading screens, and/or leveling screens.
I haven't had any issues with Carth, Zaalbar, or the PC but I also haven't given them as much attention because they didn't need coaxing to work the first time.