Large special mesh part deletes the moment I playtest

I’m trying to make a special mesh part act as the water in my game.

the moment i playtest the game the water disappears from workspace. the water is anchored, and i even tried removing the special mesh, and it still disappears. I checked if there was any scripts destroying the water and there is none. I removed every single script from the water and it still got destroyed.

this is when it disappears when i playtest
robloxapp-20241130-1203087.wmv (801.8 KB)

this is before playtesting.