Gas Arrow bugging

Some times doesnt go boom with fire wall sometimes it does sometimes it is late a few second for an explosion

same problem here! im sad

Same.

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.