Occurring in my ship, where gravity only extends to 330m below the core, 350 above, 649m aft, 450m forwards, 355m port, and 357m starboard.
Ship dimensions are: Length 1003m, Height 601m, width 619m.
Ship relative dimensions are 281m above the core, 508m forwards, 493m aft, 372m below, 309m port, 309 starboard
So, gravity does not entirely cover below or forwards, but all other directions appear to be covered.
Note: distances measured using navigation and may not be exact.
Let me know if a copy of the ship would be useful.
EDIT: this also seems to apply to the entire ship alignment and not just the gravity unit. Could be related to T758, in that areas of the ship aren't recognized as actually being present. Also like that bug the area covered by gravity increased after i started placing blocks outside of that area.