I am not sure how you are using the engine. Do you run acknex.exe seperately from your qt gui app?

But i am guessing you are using engine sdk since you can still call engine_status. i mean if you are using engine sdk and starting engine with engine_open and closing with engine_close and can still call engine_status then you also have to somehow end your qt app/loop for your process to finish. Also i do not know to which extent you plan to use qt bu i am not sure if qt is the way to go. At the very least try to merge qt message loop and engine input/message loop. And try to sync engine frames with qt. I tried qt once for a editor like gui but it in the eay i used it it required lots of sync/glue code between engine and qt and it became a real mess real quick. I think in the context of a game engine/realtime frame based apps a more immediate mode gui approach is suited better. Unity editor is such an app that uses immediate mode gui.