WaterBodyCustom seems not to work with Distance Culling settings on its own actor, either Draw Distance/Never Distance Cull or Allow Cull Distance Volume.
It only can be controlled by the CullingDistanceVolume actor, which makes it not easy to control the WaterBodyCustom culling behavior as the CullingDistanceVolume is often added to the world to be expected to control other objects, and WaterBodyCustom can not override the settings.
1. Create a new level
2. Add a Culling Distance Volume and set its Cull Distance index setting as
Size: 10000, Cull Distance:15000
3. Add a WaterBodyCustom,
4. Chang WaterBodyCustom's Allow Cull Distance Volume to disable, it's still affected by the Culling Distance Volume unexpectedly.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-195394 in the post.