Ok the devil is in the details, I had a similar fall exactly as you explained and this is the cause and solution below.
You said "I had to lean forward to regain my balance, and in doing so, quickly pegged the speed on the OW causing it to stop and send me tumbling forward."
So what happened was you pushed through the push back breaking the top speed of 12mph you will notice the nose is elevated near this point... once this happens the nose of the board will change behavior as you move past the push back point.
The change in behavior is that the nose will start dipping as you increase speed towards 15 mph and beyond. What happened was your weight was on the nose while it was elevated near 12 mph... then you made it past the push back still with your weight on the nose combined with "beyond push back nose dip" instantly made you nose dive your board in less than a second. Its not a cut out, its a crash.
This happened to me exactly two times and has never happened again because I expect it at high speeds. I still notice the slight nose dip tho.
The solution is wait for the nose dip and and shift your weight off of it as you push past the push back point. You can go even faster, the board's nose will dip a little but you compensate for it.
Like i said that exact thing happened to me, i know exactly what youre talking about. Its the nose dip after the push back phase. Watch where your weight is during that phase.
Like I said, i really ride this thing as hard as i can several times a day. Its not a lock-up or a cut out... its a crash.