I don't recall any report of losing the mast while under sail
Our flotilla Commodore lost the forestay on his Mac 25 on the return trip from Marquesas Key to Key West, while under power alone in stiff headwinds and 3-4' seas, on the last day of our cruise to the Dry Tortugas this summer. The mast came down.
Fortunately, there was no damage to the boat or people, and with the help of some of the other Cruisers who swam over to lend a hand, the mast was reraised and temporarily secured in place.
After the repair he made it the rest of the way to Key West without further incident.
In the excitement, the evidence of what caused the failure was lost, but it was believed to be that the forestay turnbuckle simply unwound. The Mac 25 rig is similar if not nearly identical to other Macs and every other fractional rig, for that matter, except the rotating mast M.