has anyone encountered a crash when

[grizzled mesa]

this causes an instant crash:

flammableHitZone.SetDamageOverTime(EDamageType.FIRE, fireRate);
                fuelHitZone.SetDamageOverTime(EDamageType.FIRE, fireRate);

[glad spoke]

Unrelated: are you differentiating between diesel and gasoline :P

but on a serious note, the game might be treating that hit zone as linked to the other ones, so setting multiple on fire on the same entity might conflict (due to game code spreading it?)
Or one of your hit zones doesn’t support being set on fire?