Honestly the prep work gets ignored sometimes. On those cramped joints, taking an extra minute to really clean the backside of the fit-up can change everything. Even a little bit of oxidation hiding in the joint will mess with your gas coverage and cause that gray haze. A small flap wheel on a flexible shaft can get in there.
Changing that torch angle to 30 degrees made a huge difference for me on pipe fittings. I'll sometimes bend my tungsten into a little hook for the real tight spots. What filler rod were you using?
Try a smaller gas lens on your torch. It focuses the argon shield better in tight corners where you're bending the tungsten. I run mine at about 15-20 CFH instead of the usual 25. Makes the puddle crisper when you can't see well.
No kidding, that gas lens trick from @faithflores is a lifesaver on thin stuff. But when you drop your flow down to 15 CFH on, say, 16 gauge tubing, do you find the shield gets sketchy if you have to make a longer arc reach? I tried it on a corner joint yesterday and got a faint gray haze right at the end of the weld.