Happened on a 331 that I chartered several times. Tight clearance between the end of the boom and the split back stay.
If you don't have the vang tightened sufficiently, the boom lifts enough during jibe that it hangs up on the stay. Got to keep the vang tight when you jibe. Also need to haul in the mainsheet quickly to a tight position when going thru the jibe to keep the boom from lifting. If the mainsheet and vang are tight, and the boom is parallel to the deck, there should be sufficient room to clear the back stays. Evidently, the boom is not hanging up when tacking; therefore, the boom must be lifting when executing a jibe.
Word of caution for you Beneteau owners, we had an incident where the boom detached from the goose neck in a leisurely sail in 10 knot winds. the boom is attached to the gooseneck by way of a ss shaft. the shaft is held in place with a cotter pin. Evidently, the cotter pin wears from movement in the shaft and goose neck. When the cotter pin failed, the shaft hit the deck and the boom flew out to leeward side of the boat. Could have resulted in a severe injury in higher winds. Moral of the story is to replace the cotter pin every couple of years to prevent an injury or damage to rig.