In your code sample, you had y-1, but in your debug code sample, you had y+1. Is there a specific reason you did that?

the was really no difference it was mainly just random block around it

We may generically have a language issue here. I think we are all debuggers telling you how to discern if a specific block is an instance of an interface, while you are wanting to search for one in your world... is this correct?

the block ... implemented IPowerContainer and had a TileEntity...

Hold everything... Your BLOCK class implements the interface, but you're testing a TILEENTITY for instanceof?

 

Maybe you need to translate the TileEntity into a Block (te.blockType) so you can test the instanceof that instead?

What I want to do is detect if a block is of a certain interface and if it is, then call a function to set some variables in said block but because the variables need to be in the nbt, the TileEntity needs to implement the interface.

It's my version of an energy system...unfortunately it only can have a single input unless I use a list

As I said the block has a tilentity which implements my interface and what my code is doing is if it has a TileEntity, then it checks if the TileEntity implements my interface

I got it to work finally....after like 20 or so hours working on it