Let's start with some information for all those who either don't know the project or just haven't dealt with it after a successful claim:
NIX is a project that aims to connect existing decentralized exchanges with a DEX manager and can thus enable each coin (yes, even bitcoin) to be privatized. How this works is of course explained in more detail in the whitepaper and is not the purpose of this article.

I would now like to go into more detail about the initial supply of the coins: There was no ICO held in comparison to most other projects, but a claimed airdrop. Since the NIX team had previously worked on another coin, holders of the "old" currency received NIX coins in a ratio of 1:2. To get NIX coins, you had to hold the "old" coins at a certain snapshot block and then prove the possession of the address with a signed message.

Now some users did not understand the instructions (or possibly did not read them thoroughly) and used an address format designed for master nodes (ghost nodes) as receiving address. As a result, the claiming process failed. However, as this was the fault of the user, the team did not support it any further. Until today.

As announced in an official blog post, affected users are now again allowed to repeat the process. Further information can be found in the linked post. It is important that you are only allowed to do this if you have submitted an incorrect claim within the actual claiming window.

Did you participate in the airdrop or are involved by any other means?

Disclaimer: I am in fact holding NIX coins and am running ghost nodes but I have not been paid for this article.