Minecraft 1.12.2, Minecraft 17w43a, Minecraft 17w43b, Minecraft 17w45a, Minecraft 17w45b, Minecraft 17w46a, Minecraft 17w47a, Minecraft 17w49a, Minecraft 17w49b, Minecraft 1.13.2, Minecraft 18w48a, Minecraft 18w48b, Minecraft 18w49a, Minecraft 18w50a, Minecraft 19w02a, 1.14.4, 19w44a, 1.15, 1.15.1 Pre-release 1, 1.15.2, 20w06a, 1.16.4, 20w49a, 20w51a
So basically, if a player where to reel out their fishing rod bobber towards block(s) above them... the game would for some reason make the bobber be stuck at OnGround:0b for a long period of time. Even if the bobber hits the ground afterwards, the bobber would still be stuck at OnGround:0b until the game decides to detect it that it's on the ground (which takes quite a while by the way).
- Cast a fishing rod towards the ground
- Use the following command to verify that OnGround is set
→ It says "unknown", which is the fishing hook
- Cast the fishing rod against the ceiling and make sure the hook hits it
- Repeat step 2
→ It does not list the fishing hook