Scopes don't jump on & off that I have ever heard of. I've been using scopes sense the 60's & I would rule that right out.
TenX is very good ammo. Maybe not the very best, but in the top 2 or 3. And as you say, your gun likes it. I'm guessing you tried Federal Match which is also $10 per 50 shots. Fed. changed the powder & now it is great in some,but not in others.
That leaves you.
Do you know when the shot breaks, where you are pointed,precisley???
If you know when a shot goes high or low when you shoot,then it might be an ammo problem. My guess is: That you have not shot long enough to call the shot & your problem is in the trigger pull tecnique that your are using.
Things to check for:
1. pad of finger on trigger
2. trigger finger not touching the wood at all, you may have to shift your grip for this one
3. same grip every time
4. same cheek weld every time,so you are centered in the exit pupil every time
5. REMEMBER TO SQUEEZE THE TRIGGER SLOWLY
Hold your hand in front of your face. Using trigger finger only, quickly snatch back on the trigger finger as if you were shooting in a big hurry.
Do this while watching the rest of your fingers.
Do you see the others twitch??
Now do it slowly. They don't move. This has to do with the phisiology of how the fingers work, & the only way to beat it is SLOWLY.
I hope this is of some help. Post again & let me know. We may need to think of something else.