When facing the direction the sun when it is setting you can reach up to the fifth block to place or break the block and when facing the oppsite way you can not..same with when faceing south you can breack/place a block and other way you cannot...

HOW TO REPRODUCE:
1.Stand against the block
2.Break the blocks as much as you can
3.Realize it needs fixed
4.Find out why it happens
5.Fix the bug
7.Add this to things fixed
8.Realize i missed 6