Issue description:

Has happened on two different occasions:

1. System is inside compact machine. Person 1 in the overworld has a grid on the top of the compact machine, person 2 is inside the compact machine using a grid attached directly to the system. Person 2 puts an item in, but it does not show up for person 1 until they mine the grid and place it back.
2. Put an item in an AE2 grid (using a bus to connect to a refined storage interface - storage is all done using Refined Storage drives). The item failed to appear as being in the system until I mined and replaced the interface.

What happens:

Items fail to appear in the grid

What you expected to happen:

When I put items in the grid, they should always appear

Steps to reproduce:

The issue does not seem to always happen, but the simplest is to setup a system where you access the storage from AE2 grid, but use Refined Storage drives. Put items in and out over and over, and you may eventually see this happen.
...

Version (make sure you are on the latest version before reporting):

• Minecraft: 1.12.2
• Forge: 14.23.0.2531
• Refined Storage: 1.5.23
• Applied Energistics 2: rv5-stable-2
• ATM 3 v5.1

Does this issue occur on a server? [yes/no]
Yes

I'm sorry, I really can't reproduce this issue.

No worries... It seems to be rather random. Probably a very specific corner case.
If you ever want to see it in action, I can always show you (if it is something that requires more attention)