I was only considering a reduction in the bullet weight and how that might affect trajectory.
A bullet can fracture in a lot of different ways.
If the bottom broke off cleanly then maybe it would only make the top of the main remaining bullet slightly shorter.
Or perhaps the wobble is what made it shoot high?
And another idea would be what if one of the fractured pieces caused some kind of a mini-collision in the bore, or some kind of minor/temporary barrel obstruction or disruption.
It could have been such a minor obstruction that maybe it could have been like 2 moving objects slightly bumping into each other inside the bore.
Not really an obstruction, but still some kind of disturbance that slightly interfered with the normal exit of gases.
I guess that speculation is the devil's playground, like trying to discover quirks and quarks in the universe.
Fraankly, I didn't think that the possible .03 difference in wad thickness would make much of a difference in powder compression and trajectory either.
At least your theory could be tested by test firing the same suspected error in loading the 2 wads.
Why not try that to see if you can eliminate that possible cause?
Intentionally load the 2 different size wads in 2 new rounds to see if you can duplicate the anomaly and then report back to us.
If the wads were the cause then it should be repeatable, right?