I use to have line twist all the time.
I didn't jump for 3 months in the winter ( i'm a sisi what can i say) and when i started jumping again I made a demo full ( just to be sure...) and i discovered i was unstable during opening.
I've realized that i put my left hand to close to my head = a soft spin on opening = a line twist.
After I've fixed this i get on heading opening all the time.