2 things stand out to me,first is an off brand arrow with a spine range that would make me supect about spine.

A WB that could be causing the arrow to push up off thebristles,if the bristles are too stiff for those arrows,then itwould be like have your spring tension too heavy on a tarditional style prong rest or vane contact in that area,with no way to correct it.

Or a combination of both.The others have also brought up some good points as well.