You're a genius as usual, now it accepts it. I get it now, DON'T think intuitively about this stuff, you have to learn these unintuitive techniques.
IMMHO, if you have 6 parameter in a flow trigger input, then PowerApps should allow all six regardless of it being required.
In this case, the Power Apps V2 shouldnt allow you to include any paramters that arent required. It only saves some us many hours of exasperation and increases in blood pressure.
Thanks again. I'll remember this little nugget of intel for sure!
Cheers