Holding down right click while being in a position suitable to placing blocks in the air won't place the blocks, only the first block will be placed.
Steps to reproduce
- Load a world in creative, superflat preferably.
- Make a line blocks for you to stand on in the air.
- Stop flying and stand on the line of blocks.
- At the beginning of the line, look at the air beside the block, in a position where you would be able to place blocks.
- Start holding down your "place block" button and moving sideways towards the end of the line.
All the blocks alongside the line are filled.
Only the block where you started is filled.
For further instructions on the bug, please check the second half of the annexed video.
I tested this on both Xbox One and Windows 10, survival and creative. Didn't work on either.