Setup:

Creative Energy Source
ME Controller
ME Security Terminal
ME Wireless Access Point
ME Crafting Terminal
ME Drive + (extra storage) Cell
ME Storage Bus, Priority 2 (ME Drive stayed on default 0)
Vanilla Chest connected to ME Storage Bus with 27 Stacks of highly valuable Creative Cheated Diamonds

Experiment:
Place a ME Annihilation Plane facing the Chest

Expected behavior:
The Chest will be broken down and added to the ME System.
The Diamonds will drop and at least a few of them touching the Annihilation Plane will be added to the ME System

Observed behavior:
The Chest will be added to the Storage Cell.
The Diamonds drop and get instantly deleted.

Originally posted as a bug report against WirelessCraftingTerminal, but this experiment revealed, that vanilla ME also causes the issues without the WCT.
-> p455w0rd/WirelessCraftingTerminal#279

Setting the Storage Bus priority to -1 and placing the Annihilation Plane afterwards will correctly cause both, the Chest and it's contents to be added to the storge cell. My assumption is, that the ME System adds the Items to the already broken down Chest, meaning the ME System keeps a Reference to it's Tile Entity and even thou the block is already dead and the Tile Entity being invalid, the ME System just adds the items there anyway.

Could be the reason for it. The inventory code in forge is a mess and can be a massive performance issue when being used on a larger scale. E.g. with AE. And for now they don't seem to care about providing a better implementation at any point in the future.

So we currently have to cut a few corners to not completely obliterate any performance, which cannot be fixed in a sane way currently. There should be a few things we could try, but it could easily be a regression for most users by solving a seemingly pretty rare edge case. Thus currently not sure, if it would be worth to fix it now.