Problem with water surface culling outside certain ranges

I’m still using the old ProjectedGrid code from JME2 - slightly updated - to render water due to the underlying geometry support.

I’ve hit upon a snag that I can’t figure out for the life of me - when I load up the scene everything looks fine, but when I start moving the camera around, at some point the surface will disappear, apparently being culled for some reason.

The whole surface has CullHint.NEVER set. I’ve been playing around with camera frustums and perspectives but it doesn’t seem to have much effect. As soon as i rotate the camera away from the start orientation, the water surface disappears.

I swear I haven’t updated any of the code lately though - and it has been working fine with older versions of the JME3 libs, but times are changing and I need updated libs.

Any suggestions for this problem?