It's on the slider and it shows to be working in calibration.
your RPM's is on the slider? although it shows to be working in calibration. have you tried messing with it in game ... while trying to take off?
test it, without the wep.... launch to the runway and go wide open throttle.....if the plane still acts as if no throttle is working, adjust your RPM slider to see if it has any effect......
it may be possible that it is "inverted"... ie... working in reverse , I know I had to go in and click the invert axis box on my RPM's once........
outside of that, I don't know what else to suggest, unless you use Sateik controller programming software and it somehow has become corrupted on this one command regarding the RPM's....
but what you have explained on how it works with the WEP but not without, seems identical to what I ran into on my CH HOTAS and RPM wheel/axis
Good Luck