too many mounting holes?
There are M1..M4 connected to "CHASSIS" - which is good
There are also B1..B4 connected directly to GND - which is bad
FMC specification says:
Rule 3.19: To prevent ground loop problems, the FMC front panel bezel shall be electrically isolated from the circuit ground on the mezzanine module. Rule 3.20: Boards shall provide a minimum of 500Vdc and 1 Mȍ of isolation between the FMC front panel bezel and the mezzanine circuit ground.