The Ruins Mod's Ruins spawn on lab, this creates unremoveable dirt and water tiles that even the clear lab button does not get rid of.
Two solutions would work good enough:
First (and best) would be disabling ruins spawning in the lab.
The second and less effective would be making que clear lab button get rid of tiles. (would be useful for already created worlds with this issue).
Thanks in advance, both for reading this and for making such a great mod!