Spontaneous hunch: This 2015 bug basher/miner❤blocker is the terrain-removing analog of the 2016 bug Turning builder at blocker separates builder from crowd that I fixed around Lix 0.7 in 2017. The problem there was: Builders would turn at blockers, move forward through air without ground, then continue to build staircases in midair where the crowd couldn't follow.

The solution was to duplicate the most recently placed builder brick when the builder turns. Thus, one brutally direct fix to basher/miner❤blocker might be:

Idea (Swing Duplication): When a basher or miner turns at a blocker, the basher/miner duplicates the most recent swing, i.e., the most recent earth-removal, mirrored according to the new direction and position.

Swing duplication doesn't have the if-if-if of idea ♠ further up. But I'll have to read the entire thread again. Downside of duplicated swing: The duplicate might end up severely displaced from the original swing, possibly allowing powerful abusable physics. I don't want this fix to become a strong physics feature to design levels around.

Will sleep over it. No matter what, I'll keep this bug in 0.10 as-is.

-- Simon