forestry:arboretum breaks walls from modification Compact Machines.

forestry_1.12.2-5.8.1.325.jar

Im Also noticing this issue, came here to report it and saw this aswell xD, it breaks the blocks because the Max size is 1 block too big from center, would need some sort of if statement to detect if a forestry farmer is placed or somehow make it unable to be destroyed by the machines.

The walls have setBlockUnbreakable() set and a few other checks to prevent players from being able to remove the walls.

Forestry is replacing blocks though, which is not being blocked. Will be fixed in the next version.