Minecart on horizontally moving blocks fall through ground under oddly specific conditions.

A minecart on a block that is being pushed horizontally falls through said block if and only if the following conditions are met:

1. The sticky piston is pushing in the -X or-Z direction.

2. The block the minecart is on will not cause the minecart to be translocated by the floor moving (to the best of my knowledge, the only block that has this property currently is an open trapdoor).

3. There are no other minecarts or boats within a 5x5x5 cube centred at the location of the original minecart.

Expected outcome:

The minecart should never fall through the floor in this setup (second image is one of the offending setups). The fact that this is directional surprises me, given that this is an entity interaction and not solely block-based.

The fact that the minecart will not fall through the floor if there is another minecart in a 5x5x5 cube centred at the position of the minecart shown seems to be an effect of some broad-phase collision detection algorithm, as the minecarts never interact directly.

Observed outcome:

When the three conditions are met, the minecart falls through the block when the piston retracts (see video).