I had this thought when i was there from 8/7 - 8/10 because the first time i went on Unchained, both shows were down.
(I didn't lose my mind, but i was disappointed, Codeman)
They were back up by the evening, so I was able to see everything, but the ONLY animatronic i didn't see working on the ENTIRE ride -no matter which time of day i tried it- was the finale Dracula.
Here was the 'solution' I came up with.
If IGOR pre-show A is the problem, you just open the door and let people walk past it and go into VICTORIA pre-show B.
If IGOR pre-show A is working, and you hear the "send them in" - "the doctor will see you now," but VICTORIA pre-show B is NOT working, they should use the screens BEHIND the animatronic to create a version of her that looks similar to the IGOR pre-show that shows her in the first room she's in on the ride, so that it pushes the narrative that you have to keep moving to come and meet her. Something along the lines of "You're almost there, please leave your belongings in this next room and load into the vehicles I've prepared for you accordingly."
If BOTH pre-shows are working but there is a FLOW issue, open both doors and let people stand and watch if they want to watch or walk if they want to walk - just like Hagrid's operated for years. They shouldn't be shutting down pre-shows for FLOW nor OPS related issues, not when capacity is nonstop like it's been. Its issues have to be technically based for the Victoria show and they're skipping the Igor show to keep people moving.