When you are using any of the 3 current tools to manipulate blocks, at a certain angle you are not able to select the block there anymore, because the outline of these tools is gone, but after you turn right to that area, suddenly it works again:
When you are using any of the 3 current tools to manipulate blocks, at a certain angle you are not able to select the block there anymore, because the outline of these tools is gone, but after you turn right to that area, suddenly it works again: