Cant fill water in an empty bucket if you are in the water

Just as the Summary says. i cant fill the bucket with water when iam in the water. creative and survival mode.
Recreate: build a small tower- 5 blocks high. with blocks around so you have 1 block space in the middle. now place water bucket directly above your head. if you now want to remove the water you cant just point upwards, you need to point at the face of the next block where the water source is touching AND be at the same heigth of the water source.