[Autumn]

Mossybark's Fungus doesn't stack per additional piece of Mossybark, it also doesn't regrow on every subsequent 3rd round just in case that is relevant. I figure that there's no utility to it if Fungusbark does the exact same thing but from round 1 instead of 3.

[Neus]

What item slots are your Mossybark items on?

[Autumn]

I see the issue, I had assumed it worked like fungusbark, I had a weapon and gloves, but no torso. I equipped a torso and saw it worked as I expected it to.