Gas Arrow does not explode

Even with the helmet or the fire barrier, the gas arrow does not explode.

Same. nothing in the notes said there was a change.

Yes, please fix! This is lame AF. Already sucks we can't get good loot, now we can't use abilities as they were intended.

It is due to ignite changes. Now, to ignite gas arrow you need:
Ignited ground (through beast, curse, or unique for example)
Always ignite modifier from beast
or just always ignite the target yourself.

However, if you use ignited ground effects, explosions do not shotgun for some reason, so for single target you will either want a beast or ignite yourself reliable.

But yes, they need to actually let helmet ignite instead of building flammability cause it is a hot garbage now.