a mod conflict isn't impossible, though it's also possible that it's just normal behavior. brick ownership isn't saved per-brick, it's only attributed to bricks with the isBaseplate flag turned on (which includes stuff like cubes), and the same ownership is just applied to bricks up the chain. you can see this p clearly if you open up a .bls file
32x32 Base" -267.5 0.5 0.1 0 1 25 0 0 1 1 1
+-OWNER 12949
8x16F" -267.5 4.5 0.3 1 0 38 0 0 1 1 1
8x16F" -271.5 -1.5 0.3 0 0 38 0 0 1 1 1
16x16 Base" -265.5 -1.5 0.3 0 0 38 0 0 1 1 1
1x16" -267.5 6.25 0.7 1 0 40 0 0 1 1 1
1x12" -270 -5.25 0.7 1 0 40 0 0 1 1 1
1x8" -263.75 4 0.7 0 0 40 0 0 1 1 1
1x8" -271.25 4 0.7 0 0 40 0 0 1 1 1
1x10" -264.5 -5.25 0.7 1 0 40 0 0 1 1 1
you'd have to determine for yourself if this explains the problem you're having tho