Bubble columns are not turning to stone when in contact with flowing lava

The bug

Bubble columns are not turning into stone when in contact with flowing lava.

How to reproduce

1. Put a 3x3 area of magma blocks under some water.
2. Empty a lava bucket 2 blocks above the water level, at a corner.
   →  Bubble columns do not turn into stone, instead the lava flows over it

Code analysis

Code analysis by [Mod] Avoma can be found in this comment.