Beam weapons and 'unfolds to fire'

I have a ship that unfolds to fire. This works fine, except that when firing a beam weapon. It opens and closes as it should, but while firing, the animation seems to get stuck cycling between the last and 2nd to last frame.

I tried some different life expectancies and reload delay, but it didn't fix it.
Is this a known issue? Or is there some work around? Do I have to add another frame to the animation that duplicates the last frame?

I wonder if it's related to the same thing that makes hypergates loop the last frames when they open. Does it just affect your beam weapons, or all weapons in general?

Only the beam weapon, the other weapons work normally.