So I've uploaded a new build (GUNSWINGER01.zip) which maybe fixes the issue. Do you mind trying it out to see if you're still getting the same behavior for the billboard sprites?
Unfortunately, it's still happening. I also tried restarting my PC and checking my drivers, but nada. Also checked the task manager, it seems to only be using my dedicated GPU, not the iGPU if that was a concern. It's not a super big deal, the game's still playable. So maybe give it a rest and see if anyone else has this issue, should narrow the problem.