I'm using a SRAM Rival chainring with a GXP BB (bdop). I changed the BB last November just before the wet season, but in the last couple of days it started creaking badly, almost at half rotation. It's got a constant ticking pattern when the crank arms are at a certain position. I've tried many solutions that I could think of to no luck. I cleaned up the BB shell, inside the BB (though I didn't disassemble the bearing as it's still rotate smoothly), the crank spindle, the BB thread, and the BB shell thread, and they're not even that dirty even though I've done many wet rides. I've tried putting grease and/or loctite on either thread. I've changed to another pedal and to no effect. It's still ticking when I'm pedaling off the saddle, so it's not the saddle or the seatpost. Any symptoms that I might miss?

When I do a one leg drill, it appears the creaking is only on the non-drive side (left leg), there is no ticking on the drive-side. Oh and it only started creaking when it's about 3km into the ride. I can't emulate the sound when the bike is on the stand no matter how hard I swing the crank arm.

I think I'm going to loose my mind with every pedal turned. I even softpedal on quiet roads every time I pass someone, just to suppress the noise.

Check your headset bearings. In lots of cases in my experience(humid climates & sweaty riders) after I eliminate the BB as the source of creaking I pull the stem and spacers to find a rusty nasty headset bearings. Its sounds to me as if the creak is non rotational, however not being able to emulate it in the stand doesn't completely rule anything out. I'd bet on the headset though. Check it out and report back. Im curious. Are you torqueing the non-drive side arm on?

Remove the BB and clean everything. Apply grease to threads and reinstall to torque spec.
Apply grease to spindle and to bearings. When you install the crank make sure there is adequate preload.
It may not be the BB. Depending on the design of the Sram crank, it maybe the crank arm attachment to the spindle if it is left leg specific.

Also, it could be your left pedal. How are the bearings in your pedals? A tick every turn can even be your saddle.

Good news is....BSA is the best and most reliable BB for clicks and creaks. I am not a fan of Sram cranks...prefer Shimano or Campy cranks with BSA...but hopefully you can quiet it down.
Make sure you use a torque wrench on the left arm attachment bolt.

Good luck

1. Check your rear QR skewer. Lots of "BB creaks" are a slightly loose quick release.

2. Check your chain ring bolts. I have a Campagnolo Centaur crankset that was creak central, and I removed, greased, and reinstalled every chainring bolt and it has not creaked again.

I had a creak that I first thought was the BB/crank. It wasn't. Then I thought it was the headset. It wasn't.

It turned out to be the brake cable ferrule. Just the tiny bit of moving the bars changed the angle/pressure of the housing which caused the squeak. A shot of WD-40 fixed it.

Crank hitting the FD cable? Check all the chainring bolts are tight. Try a spare set of pedals even just platform ones, LBS or friend should have some lying around. How about your bottle cages, saddlebag, etc? One ticking sound I had once was my rear blinky contacting the brake caliper.

Also worth running through the list here: Creaks, Clicks & Clunks...