Pretty Beaches seems to work perfectly in Single-Player Survival mode.

In Multi-Player Survival, the effect of Pretty Beaches is random. Sometimes it fills in water, other times not. I have not been able to see any pattern to it.

Observed in:

Minecraft 1.14.4
Mods:

• Forge 1.14.4-28.2.1
• Pretty Beaches 1.14.4-3.0.7

Closing since 1.14 is no longer supported