"Out of ammo(20mm)" bug?

[Adler_]

Hello, I'm getting "out of ammo(20mm)" bug when flying 109's in multiplayer. Currently happening in E7 and i'ts just killing the fun. 
It happens, usually short after you have been using them or if you just fly long enough. The message just appears and you're out of ammo. 

Few minutes ago was flying for solid 30min trying to spot, and when the time came to fire I was out of 20mm. 
As if something "eats up my rounds"..maybe the engine is hungry.