Issue Description:

I cannot sneak-place any block onto any machine with UI when my iron backpack is equipped on my back.

What happens:

The block simply disappears, afterwards if I right click anywhere the block suddenly appears. Please see the video .

What you expected to happen:

The block is placed where I put it even if my backpack is equipped.

Steps to reproduce (important):

1. equip an iron backpack
2. sneak and try to place a vanilla hopper (any block) onto a vanilla chest (any block with UI)

Affected Versions (Do not use "latest"):

• IronBackpacks: IronBackpacks-1.10.2-2.2.19
• Minecraft: 1.10.2
• Forge: 12.18.2.2171
• Modpack: FTBPresentsDirewolf20110-1.1.3-1.10.2 (https://www.feed-the-beast.com/projects/ftb-presents-direwolf20-1-10/files/2353000)

Thanks for the bug report!

Does the equipped backpack have a quick deposit upgrade on it?

Yes, it's Storage Emphasis with:

• Mining Filter Upgrade
• Quick Deposit Upgrade
• Void Filter Upgrade
  installed.

Alright, I'll look into it! I'm busy with finals coming up in the next couple days, but I'll look at it as soon as I am reasonably able to.