Hi :)

Four truffle mushrooms in Valley cave are not respawning, this has been tested over 2 weeks just to make sure. They never respawn.

In the past, these were always gatherable. However, a few weeks ago, a rock was removed to expose a mushroom that people had trouble gathering. Unfortunately, in the process, four nearby were accidentally broken.

Exact locations: 

To anyone outside the alchemy world, would probably think "WTH, who cares" but it's really important for critical damage potions. 

Thank you for your time!

Exact location 

Yep, I've experienced the same thing