So there's a quest where you have to set a volleyball net on fire.
I've covered it with gasoline, and I have fire weapons, fire grenades, and a fire nova shield. I've tried all three of those, and none of them will catch the volleyball net on fire.
With my other character, one shot from a fire sniper rifle caught the net on fire, but with this character, no amount of flame shots, grenades, or explosions from ANYONE in my game will set it on fire.
I had issues as well. I had a pistol with fire damage and no matter how many rounds I put into it, it just wouldn't light. I resorted to using a grenade mod that had several fire grenades pop out and it worked. --- "I'll help you fluff your Garfield if you know what you mean?"