The nvidia profiles and SGSSAA settings are completely unrelated. It's not really an official setting but from what I read it was a bug at some point but people loved it so nvidia left the door open and you can sneak your way in via the inspector.
That also explains why it's pure lottery when SGSSAA will work or not. Sometimes using a bit that works in a comparable game engine (or the same) gets it activated, sometimes not using anything at all... The behavior flag is a weird thing. It's needed for some games when running ingame options only but once you fiddle with the inspector it can make things work or break.
Most dx9 titles work with a custom bit someone found out, no behavior flag and then forcing (or enhancing if the game got inbuilt MSAA) SGSSAA on top.
Sometimes only normal supersampling works, sometimes one of the combined, weird ones work.
They also all do something differently! Some are sharp, some are blurry, some are better for "real objects" similar to MSAA, some are really good on transparent things.
Assetto Corsa is an easy game. Behavior Flag at default or off both work. Also it works without a custom bit but it might look a bit differently with some bits.
In the end I went back to 8x MSAA with MFAA enabled.
Why? Because SGSSAA triggers on SMOKE and DIRT (or explosions/magic/whatever for other games). So everything is beautifully running at 40% GPU load on my 1070 @1080p single screen until someone directly in front of you goes on the grass and the load goes up to 100% and your fps down to 20!
So it was SGSSAA or Smoke+Dirt. Since Smoke+Dirt are nice feedback for locking tyres, going too wide or seeing if someone does one of that, I decided for race pace against SGSSAA.
LOD BIAS:
NEVER use this for sharpening when using SGSSAA. It's an ancient solution that brings a lot of problems!
In Counter Strike you got banned for it until an auto-reset was implemented because you could see enemies better at positive LOD settings.
In some games a negative LOD bias increases GPU load massively because Object LODs are increased by way too much etc etc.
What was a nice settings but is broken since the GTX 7xx series was CLAMP for the LOD settings. This allowed for normal LODing but blocked negative settings so fine lines weren't overly sharp and didn't start to flicker.
Sadly the setting is broken - otherwise you probably wouldn't need such high amounts of AA in games like Assetto Corsa...
How to fight blurriness:
Use reshade/sweetFX/whatever works for your game! From my tests Lumasharpen induces the least flickering while sharpening really well.
Conclusion:
Buy a 1440p or 4k screen, lower graphic settings until your GPU can handle it and get used to flickering/shimmering/pixel crawling. You will save lots and lots of time and frustration and just be able to enjoy every game without much fiddling.
I tried Witcher 3 and pcars1 for example with all bits I could find, trying to force everything that's possible, wasted DAYS!
Then played for some time with forced nvidia FXAA on top and Reshades SMAA on top and then sharpening it up again... It was okay but texts were difficult to read since they were affected too.
Then I slowly became less bothered by that all and stopped fiddling around. Once you get used to it you stop seeing it and nowadays I just enjoy games as they are.
Also the newest games have TAA, which does a great job in ACC, Assassin's Creed origins, Battlefield 1, For Honor and F1 2018 (2017 was really blurry and bad when standing still!!).
Throw some Lumasharpen at them and get happy