The bug

You are unable to use waterlogged block to fill empty glass bottles. This affects both the player and dispensers. It doesn’t even work when aiming directly at the waterlogged block, relating to MCPE-56024.

To reproduce this with the player:

1. Place a slab
2. Waterlogg it
3. Try to fill a bottle using the waterlogged slab
4. It will not work

To reproduce with dispensers:

1. Place a dispenser facing into a waterlogged block
2. Fill it with a glass bottle
3. Power it
4. The dispenser drops the bottle instead of filling it.

Expected result: Players and dispensers are also able to fill bottles using waterlogged blocks.

For hand animation playing when trying to fill the glass bottle see MCPE-60824.