(FIXED) block at x y z not being correct when testing for energy in gui update tick

could you clarify what is triggering the procedure? sometimes just xyz blocks don't work, so please clarify

I see the raytracing solution. As OP has said, the player might move after the gui is opened, which might cause problems with that solution. What you can do is store the block's coordinates in the player's scoreboard in a procedure where the x, y, and z are still accurate, such as in the procedure for the trigger "when block is right clicked". And then, in the GUI code, use the ones stored on the scoreboard rather than the ones passed to the GUI procedure.

I think the reason why the GUI values are incorrect is because it gets the x, y, and z from a "extraData" buffer instead of just taking them in as parameters for some reason:

public MyGUIMenu(int id, Inventory inv, FriendlyByteBuf extraData){
// ...
// ...
if (extraData != null) {
    pos = extraData.readBlockPos();
    this.x = pos.getX();
    this.y = pos.getY();
    this.z = pos.getZ();
    access = ContainerLevelAccess.create(world, pos);
}
// ...