I noticed the Z coordinate on line "XYZ" when in F3 mode is incorrect, but "Looking at" and "Block" coordinates are correct. This doesn't happen in 1.11.2, i just checked it.
If you look at the screenshot I've attached you can see that even though I'm looking in negative X direction the Z coordinate in front of me is 1 lower than where I'm standing.
I'm sorry if this was posted by someone else already, I couldn't find it.