Great Mothers + Galactic Legends = Bad

So, I tried twice to use Great Mothers as a fifth character in a team led by a Galactic Legend to get a feat in Conquest.  The first GL was Jedi Master Luke, and the second was Ahsoka Tano.

Both times, after the Galactic Legend used their ultimate ability (for the first time in Ahsoka's case), the Galactic Legend visually disappeared from the game screen, and the battle would just stop happening eventually.  Last time, it was an enemy's turn, and they just weren't acting.

Not sure if this is limited to Conquest or not, and I don't know if it's only because the GLs change their appearance when they use their Ultimate, but I thought I'd bring it up.

Thank you.