Hey I don't know if I'm just doing this wrong or what, but I want to ban an item in just the overwolrd, which I am pretty sure is Dimension 0. So I use the command /blockitem ban 0, while holding an item (the item ID isn't recognized by the mod for some reason) and it successfully bans the item; however, if I go to another dimension like The Deep Dark or The Nether or anything, the item is still banned. Any clue whats going on? I've tried several items as well.

Can you get the Blacklist.JSON out of the world and post it here? Drag and drop it in or post on a text hosting site please!

Could I just post it like this since I just deleted it and added one item to test?

{
  "__GLOBAL__": [],
  "0": [
    {
      "item": "ExtraUtilities:enderQuarry",
      "damage": "*"
    }
  ]
}

I can still use pastbin or something if that makes a difference?
https://pastebin.com/hZmkqFih

Makes sense! We are running 1.7.10-1.2.0.8

This works, Its easier to read when posted somewhere else as markdown can make a mess of it.
What version of the mod are you using by chance?

Ooooh geez, 1.7.10.... Give me a bit to get something thrown together to test with. Last time I recall working with it things worked fine but that was some time ago... I also might have only been using global bans too.

Ah sorry about that, I honestly thought this was just me not understanding something xD

Seems to work fine beyond the lock item showing up backwards when switching DIMs.... Not sure whats up with that.

Try placing the items in the DIMs they are allowed VS banned. I tested in single player that's all FYI.

I've tried placing them but the only way it works is if I spawn in a new item, but it will work even in banned worlds if I do that. I've also tried transferring it between players and that doesn't seem to work either. Could just be a server issue then?

It might be. I didn't spin up a server to test with as we are moving off 1.7.10 - 1.10.2, Especially sense we started moving things to 1.12 just recently.

I'll leave this open and see what @dries007 thinks as its up to him to get it fixed or not. I couldn't reproduce it in single player though.

I understand, only reason we are sticking to 1.7.10 is due to some mods never getting updated past here. Thanks so much for trying!

TBH if its a small fix he is fairly nice about doing so. Keep an eye on this as it will be the first thing he looks at tomorrow.

First: OPs bypass the restriction.
If that's not it, try moving the json file from the config to the world folder (or vice versa).
I can't reproduce this issue on a 'vanilla' server. (I used wool and the nether and it worked.)