Put the summary of the bug you're having here

What I expected to happen was...:
I expected to place a block upon right clicking.

What actually happened was...:
I right clicked, a block appeared (the F3 debug screen showed that the block I was looking at was the new block, cobble in this case) and then disappeared after a short fraction of a second, returning to my inventory.

Steps to Reproduce:
1. Stand at XYZ: 232.702, 12.00000, 295.300 facing north or 275.700, 12.00000, 248.169 facing east (the facing direction seems irrelevant other than the location of the block to be placed)
2. Right click on something so that a block would be placed in the direction mentioned (north, east, respectively) at the location one block away, within a fraction of a pixel of the player's hit box (see attached images - screenshots taken shortly after attempting to place a block)
3. Watch the behavior described in the previous section take place.