Hi @Amawang,
Are you running the fascia on it's own? The issue looks typical of a limitation of our bending model with cloth. Sometimes when cloth is pushed into a tight area like under the arm, it can have a hard time unraveling.
One solution is to have a tissue coupled with a cloth. This will stabilize the fascia and reduce the amount of trapped vertices. At the time of writing, our cloth model doesn't support self-colliisons either which would help resolve this issue.
The solution I would highly recommend though is to not solve a fascia at all. If you get a moment I think it would be beneficial to watch this video: