Yes I can relate, my shaft broke right inside hub on taper/keyway section bolted to the tranny on my 2014 F21 249 hrs, which was just 2 hrs on the water after a full service when I was just cruising at 20.
Got a tow back to base, lucky I had the PSS with collar as this stopped my shaft pulling out.
I investigated and found the design fault on forum. My dealer replaced shaft (covered by MB) and upgraded engine mount bushes (Indmar accepted fault, and dealer was pursuing cost to replace from them) after I wrote a very detailed complaint about this design fault.
GOOD LUCK