food for thought,
Is it possible that the starter engaged the fly wheel and stuck there? Now the fly wheel is locked by the starter. Something freed itself up and I rode the bike home. It starts as if nothing happened. I probably have ridden at least twenty miles and it is AOK. Still confused.
That happens to my Ford 8n tractor all the time. The ring gear (on my tractor, anyhow) more often than not stops at the same
place, and now, almost 60 years later that section of teeth on the ring gear are gnarly. My buddy Dan came over to look at it,
and we filed down the gnarly teeth... now, instead of locking up there, the starter just spins on those teeth, so quite often I have to
put the tractor in 4th gear and rock the rear wheel back and forth (imagine giant beads of sweat flying off my brow while
I'm doing this

) until I move the ring gear to an adjacent good place so I can start it.
The tractor man is scheduled to come and fetch my tractor and break it in two and put in a new ring gear in a week or so...
So this is a long way of saying, yeah, I guess the starter could have locked up on whatever passes for a ring gear on your Valk, but
I can't imagine any benign reasons for it to have done so... you don't want to have to "break your Valkyrie in two" and replace the
ring gear...
-Mike