[0.12.2] Inserters don't prefer close side on underground belts / symmetry

[Alvin853]

As we all know inserters prefer to pull from the close side of a belt when grabbing items, which makes for nice symmetric setups. But I noticed that while my setup is perfectly symmetric in all aspects, I'm getting a huge imabalance between the two sides of a belt. Hunting down the problem I noticed: when grabbing from underground belt entrance/exit going south->north inserters prefer to grab from the left side, no matter which way they insert. Example:

As you can see, the setup is symmetric from the outside. I started both chests with 300 copper plates, but the left chest (red wire) only filled up the right side of the belt and had to stop, while the right chest (green wire) is constantly putting onto the belt because both inserters taking from the underground belt are grabbing the plates on the left side.
The same setup was working fine in 0.11.22, with inserters always pulling from the close side if possible, so this seems to be a bug to me.

[kovarex]

Thanks for the report, it is fixed for 0.12.3 now.

[Alvin853]

It seems that the bug is also/still there for other rotations of underground belts, although not as consistent, so less noticeable.