"Get Block at x y z" doesnt work in "While this GUI is opend thic"

So my problem is that i want to check for a block that is under my custom block, which is right-clickable and opens a gui, standart stuff.

I have a Procedure set in the GUI in "While this GUI is opend tick" which contains this:

If: is "campfire" the same block as: Get block at x: x y: y-1 z:z

do: Set 1 "stone" in Slot 3 of the currently open GUI of Event/target entity

and yes, if i remove the "if" part, the item will just get put in the slot every tick.

the thing here is, that when i test in the gui with a sprite (sprite display condition) that only shows when the campfire is under the block, it will apear as normal. for me, that means that my custom block is saying that the campfire is there one time, and another time its just not working.

i tried replacing campfire with a dirt block, didnt work. i tried changing the y to for example -0.5, didnt work. im losing my mind help please :(

pictures:
https://drive.google.com/file/d/1ze_a9sYYz9g4w4TgtymVa0Ol5Y89aU7l/view?usp=sharing (in minecraft example (important))
https://drive.google.com/file/d/1w-iINKUHHEayLFDhT35coy9zYdKmdBdB/view?usp=sharing (the GUI)
https://drive.google.com/file/d/1j8svphrie0SL_duQ4GinGiPIs7FXIsc_/view?usp=sharing (sprite display condition)
https://drive.google.com/file/d/1hqnhz-RN75_KLIxWlUA7FC0GE9oMaMA1/view?usp=sharing (while the GUI is opend tick)