Barriers are automaticly being lit on fire

Hi,

My SpongeVanilla server (BETA 248) has been up and running for a few days and I noticed something strange since I created a roof of barriers to stop players from getting out of my KitPvP map. The barriers are automatically being lit on fire during the normal day/night-cycle. The fire doesn’t break the barriers.

Screenshot:
PS: The floating flames in the background are on top of barriers.

I do not have a explanation for it and I’m not sure where is should report it.

But is this normal?

Maybe a thunderstorm caused it? If Minecraft considers them as solid block the lightning will hit the barries instead of the underlying block.

Do you have any experience from another server (e.g. Vanilla, another implementation) that would show this only happens on Sponge? It seems to be generally possible to lit barries even though the fire seems to stop after a bit just like with normal blocks.

I’m sorry, it was indeed a thunderstorm.