Mixture Controls Stop Working

[EZ1]

I have my mixture adjustment mapped to the left and right arrow keys. Yesterday, I was trying complex engine management for the first time now that I have most of the other controls ironed out. Things were fine in the Spit, but in the Hurricane, the I lost control of the mixture at some point. The keys just stopped working right. The left arrow (increase) stopped responding completely and the right arrow worked intermittantly and eventually stopped responding too.

Also, when the keys were responding, I could not get the mixture above 100 like I could in IL2 Classic.

Are these bugs or am I misunderstanding something?