EDIT: I think I solved my own problem- see edit at end of post.
Leaving post as-is, in case it helps anyone else.

I have been having trouble getting GTAV (and other steam games) to detect my Logitech G29 wheel. In the past I had this working fine- but I recently did some fresh installs and now I am having issues.

After fulling uninstalling/removing the wheel's driver, reinstalling- still didn't work.

Then, after reading a tip online somewhere, I uninstalled/reinstalled Steam. (but kept my steamapps folder so I didn't need to re-download games)

After the fresh steam install, I got my wheel to work in GTAV again. Yay!

BUT

Then I played a different game, one that requires messing with steam's controller settings, which is a part of Steam's Big Picture mode, in order to get my sony DS4 to work. So I got my controller working there in another game-

Then I go back to GTAV, and the wheel is no longer working.

Its weird, when I first plug my wheel in, windows detects it, at the wheel spins to do its auto setup/calibration thing. Turning the wheel, you can feel the spring feedback is engaged.

The moment I launch GTAV from steam, I can feel the spring feedback in the wheel go limp/ turn off.

Its like something about steam's controller input handling kicks in as soon as GTAV is launched, and it no longer detects my wheel.

But Logitech's control software still detects the wheel and seems to think it is working.

I read one suggestion to open Steam's big picture controller settings and uncheck everything. I've tried that but no change- wheel still not detected in steam games (I've tried GTAV and Dirt3).

So to wrap this up-
Does anyone have any tips on getting steam games / GTAV to detect my Logitech G29?

I want to be able to use my wheel in GTAV, but still use my DS4 controller in Big Picture mode with other Steam games. Currently it seems like I can't have both- The wheel only works after a completely fresh install of steam before ever launching Big Picture. After configuring the DS4 in big picture, I lose the wheel.

EDIT:
I got the wheel working again, and here's how-
It was the fix of opening steam's controller settings (which opens in Big Picture), and then unchecking all boxes, and then CLOSING STEAM. Then reopen steam, launch GTAV, and my Logitech G29 worked.

So the fix was making sure to fully close and reopen steam after altering the controller settings.

Thanks.