Just tried some various broadheads mounted in different configurations, and reporting the results.
2-blade non vented Magnus. Mounted vertical and had arrows wobble to target. Hit target erratically. Then mounted horizontal. Had good arrow flight and hit targets at or near where I was looking at.
3-blade Snuffers. Mounted V up. Wobbly arrow flight. Then mounted blades aligned with fletching, good arrow flight, good accuracy.
Set-up was 64" 57lb@28" longbow. FFstring. Pulling 28". 29" arrows spined 60/65. 125 grain broadheads.
Hope this helps
I think your arrows mayber a bit under spined.
You should have found no difference at all. Sump'n up with your arrows.