With SW2016, and with one of my colleagues using SW2015, our studio is seeing increasing issues with the Mutual Trim Feature (besides the known ones) when rebuilding the tree and/or simply editing unrelated parent features and then rebuilding. Have searched the current SPR database and I see nothing on this particular symptom. My colleague had to resort to doing multiple standard Trims features (in place of a single mutual trim) just to get his FM to rebuild reliably. I too had an issue with a approx. 250 feature master model and half way down the tree the mutual trim when successfully build would consistently fail when rebuilding the tree. If you edit the Mutual trim, it is missing one of the two selections in the "keep/remove" selection dialog. Reassigning the selection and rebuild fixes the Mutual Trim... but do a Cntrl + Q and the feature Mutual Trim fails all over again.
I've always been suspicious of the Trim feature because it relies on user selection on the model directly in the viewport to determine the trim areas. How SW keeps track of that 3D selected "zone" I can not fathom - can this be the root of the issue?
I wish I could show it here but the data is proprietary. When I get some time, I'm going to try to submit an SR to my VAR. Wondering if anyone else has seen this?