What I expected to happen was...:
I would get the Dolphins Grace effect from a nearby dolphin which was in glass box  surrounded by water. This provided dolphin's grace effect in 1.13, 1.13.1, and 1.13.2.

What actually happened was...:
I received no Dolphin's Grace. 

Steps to Reproduce:
1. Make a 5x5 glass box surrounded on all sides by water
2. Remove all water from the box except for bottom level
3. Spawn a dolphin in the box

4. Swim by the glass box with dolphin inside (within distance to receive dolphin's grace) and observe you do not get Dolphin's grace effect.

I believe this to be a bug because it was possible in 1.13 to get Dolphin's Grace from this setup but it is not the case in 1.14 or 1.14.1.

This bug possibly relates to MC-148635 but this has different triggering conditions so I believe it deserves its own report.