ethan94120
Hello again. Just want to check when you say "fascia" you are referring to the fat right? Fascia tends to refer to a now obsolete workflow where people were simulating a sheet of cloth in between the muscles and the fat.
Hard to tell from that playblast if there are any self-intersections.
You can select all your zbone meshes on a problematic frame and run Ziva Tools > Find Self Intersections
Also if you haven't already, consider solving the muscles and fat at the same time. Sim times are slower but results are much more stable, and tend to look more natural.