More info, this is a ring held onto another component by 32 screw fasteners.
Examiniation of the mesh at the interface between the 2 components reveals:
1. Every other fastener has a BIG separation test diameter, (or conversely, every other fastener has a small test diameter). This is depsite all fastener definitions are the same.
2. The mesh shows that 4 of the fasteners do not appear to have a separation test diameter created at all