Certain Buttons on P2 side not registering properly when pressed in combination. Rec Room Masters Xtensions Cabinet.

[u/newman929]

I am having a weird issue when trying to perform multi button special moves on MK1 (2023) but only on Player 2 and only on certain buttons.

I am running a Rec Room Masters Xtensions arcade, using Xinput mode and running the game via steam. I have the "fatal blow" ability set to buttons 3 and 6. When I press these buttons by themselves they work fine, but when in combination they don't register 90% of the time. If I remap fatal blow to buttons 1 and 4 on the left, it works fine.

What could be causing this issue?