Apologies if this has been raised before, but I've tried searching and not come across the same behaviour.
I have a set up as shown in the picture for unloading ore from a train. The lower left hand inserter is removing ore from the train, and instead of inserting into the chest like all the others, it is removing ore, "placing" it below the chest (you can see a piece of ore in the inserter's claw). But the ore isn't being placed, it is just disappearing.

This set up was built using a blueprint, and I have other versions functioning fine without any issues. The system is backed up, and all the other chests are full. However the left hand chest is not full, and isn't getting filled by the inserter. I've tried removing the inserter and replacing, and the issue persists.
Any help much appreciated.
Cheers,
Simon
edit: it is clear that the left inserter has been putting ore into the system as the belt is full of ore, so I picked up some of the ore to see what is happening, and the left hand inserter "passes" the ore to the inserter below it, which then places it on the belt. I.e. the chest is completely bypassed. When the belt is blocked, the ore just disappears. Removing the chest stops the inserter taking anything from the train once a piece of ore is placed on the ground (as it should). So somehow the chest is messing up the inserter's behaviour.