Water Z position different to editor position when I run stand alone game

(Apologies for spamming questions today!)

In-editor window I have a water level (Water Body Custom) like this at Z = -50:

but when I run as Stand Alone Game, the Z goes to 0 and I get a water level like this:

Any idea what’s going on?

Same issue. The ‘water plugin’ is extremely unreliable.