This bugs appears to happen after the release of 1.13 and later.

In Minecraft PE (IOS), when in third person view (back), it is not possible to place a block when my finger is placed even though the place where I want to place the block is just right in ront of my character.

I also noticed that if I place my finger 1 block to the right of where I want the block to be, the block will be placed in front of me. It is impossible to place block above where my character is standing.

This also happens to some extent when I am trying to break a block.

Therefore, it is difficult to place blocks where I want the block to be.

I have not played third person view (front), so I cannot comment if this bug occurs in this view.