The Bug
F3 screen's 'targeted fluid' fails to identify bubble columns, instead identifying them as minecraft:water. See attached screenshot.
This is inconsistent with the command `/execute if block ~ ~ ~ minecraft:water`, which if done to a bubble column, will fail, and will only succeed with minecraft:bubble_column, so that's what the targeted fluid should say.
The fluid is correct - bubble columns are blocks without a hitbox. The
/execute if block
command doesn't test for fluids, it tests for blocks.