(Copied from my post in the bug report, just announcing here, for fellow Riptors)
Riptor’s Predator Stance MK whiffs Mira completely if the characters are touching each other, and with each small step back will whiff one less time.
So at a distance, all three tail pokes will hit.
Point Blank Range all three will whiff.
A slight step back from touching, the first poke will hit, the second and third whiff.
A slight step back from where the only the first will hit, and the first and second will hit, but the third whiffs,
The range required for the whiffs is very close, but if you’re following up a blocked headbutt with Pred MK, at least the second and third will whiff, sometimes even the first.