[0.15.16] Stack inserter gets stucked

[isacikgoz]

As you can see, the stack inserter (also tried with fast inserter) get stucked after few successful inserts. Long handed inserter is not affected with this issue.

[Loewchen]

If the right side is close to full speed it can not grab from this position. Post the save please.

[isacikgoz]

I've edited the first post and attached the save file.

[Rseding91]

This is similar to the burner-inserter can't pick up from fast belts scenario: the available space for an inserter to pick up from an underground belt is tiny and at full speed the inserter can't grab items off the express underground belt.