I noticed that with a particular rotation of the camera (and only one?), part of the shadow of the sphere disappeared:
It’s the same problem as when the type was HALF_FLOAT but it appears much less often because of the additional precision of FLOAT. So I’m not sure there’s much we can do, we’d need even greater precision…
Is it an option for you not to authorize looking straight down but to limit it to a small angle (if it is an arc rotate camera, not less than 5° for the beta angle, for example)?