Duplicated matinee issue

I have a project that requires a lot (approx. 100 orso) similar animations with only tiny variations. I have created a single matinee for the first one, which I hope to duplicate and adjust for all the others.

However, the duplicated matinee (duplicated in the browser, then dragged into the scene, then opened for editing) has no actors in any of the groups.
I can manually add the actors back to the group, and they appear; and the preview works, but when I save and close the matinee, the groups are empty again.

Everything else about the matinee seems to work (the controller for the new matinee shows up fine in the level BP and suchlike).

I would really hate to have to create these matinees from scratch by hand and am relying on being able to duplicate and adjust them. Is this a bug? Is there a workaround?