I'll try creating a fresh server later, to see if it's somehow that the age of the server (same one since the launcher came out) that's causing this. I'll also try removing all blueprint permissions for the time being.

Can happen with build blocks too, not just ship cores. esp. if the build block has no space above it (even with plenty of space to the lower sides)

Glass also still has plane issues when rendering (connected arias of glass render some internal planes, which appear to be based on position, much like the lighting bugs).