Here's a bug report where Active Provider Chests do not get their items picked up:
APC:

bot network and matching storage chest:

As seen in the screenshots the roboports are powered and connected.
Switching the APC to a different chest and putting a new APC again on top immediately made some bots fly to the chest and unload it.
1. How can I identify the broken chests and fix the factory?
2. Has the reason of the two bugs been found yet?