Inserter confused in multi item furnacearray

[Senil]

I know that this isn't the most usual way to smelt your stuff (copper ore, iron ore, iron plate).
But a friend and I tried to make a huge furnacearray that you could put all things that should be smelted on one inputline and then sort it out in a sorterstation on the other side.
It works fine as long as it's just copper-/ironore, but then you add iron plates to the mix, the inserters gets confused.

Like in the picture below, one inserter grabs a piece of copper ore and try to inert it into the furnace that already holds iron plates.

If you remove the ironplate(s) in the furnace it works for a while, but eventually the same occur again.

We have tested on both singel-/multiplayer in 0.12.4 and 0.12.5. Both of us have mac, so not tested if it's the same in windows.
Here is a link to the savegame and log. Link

[Yttrium]

My guess is that this is intended behaviour, you will have to find your way around this and make sure Iron plates will always arrive in arrays of 5.

[kovarex]

Well, it isn't really a bug, as the inserter would have to know what other inserters have already something in their hand.

We decided to consider these problems to be part of the gameplay challenge.