my bad, this is entirely a different bug than what I was referring to
changing the scale of the mesh (on Build Settings → Build Scale) to something slightly different than 1,1,1 (but not too slight) also fixes it. so 1.05,1.05,1.05 or 0.95,0.95,0.95 actually fix it as well.
interestingly the default Cube (which is also 1x1x1m) doesn’t have this issue because the DF resolution scale is saved to 2.0 by default. setting it to 1.0 brings the problem to it as well, which means it’s not a topology problem (1M_Cube has 1 quad per side while Cube has 4 quads per side)
it’s like the DF generation has troubles when something is exactly 1 meter at a DF scale of 1.0 