Cannot cut/segment Compound Path

Thank you. I neglected to post a reply to my thread and close this.

So, first off I deeply appreciate your suggestion, as always! I had tried the approach of "divide objects below" and "Split into grid", and again just now after reading your post to confirm, but it either does nothing at all or I get "The filter cannot complete because more than one object is selected." I swapped the order of the objects, I tried with both selected, and I tried with each slected independently.
Im very interested in knowing why this is happening. But I have a feeling it'll either require another video on my part, or to share a project file.

However, regarding this particular project, I was able to come to a solution. I'd actually been doing the "solution" repeatedly, always ending up the same bad results. . . because I had the objects in reverse order. What I  was able to do is take a rectangle shape object, place it behind the mural compound shape, select both, use "intersect" in pathfind, and then turn the resulting shape(s) into a compound shape. Viola.
Im still going to mark yours as the correct answer though because I figure it's something Im doing wrong and yours would be a much more straight forward approach.