Query Filter value not working with record or local variable

I have a record with shops, and then also a record with products. I assign a Shop ID to each product, depending on which shop sells this product.

So for example, the product with ID 47, has a value 20 in the ID Shop Column, because the shop with ID 20 has this product.

Then I have an Interface with a report that you acces from each shop. If I acces to the shop with ID 20, I want the report to be filtred in a way that it only shows products with Shop ID 20.

My interface, my query and my filter works correctly when I test it with an integer in the value:

But when I try to get this value from my rule input which is a data type, it doesn't work, and shows this error:

Could not display interface. Please check definition and inputs. Interface Definition: Expression evaluation error at function a!gridField [line 4]: Expression evaluation error at function a!queryLogicalExpression [line 33]: The a!queryFilter function has an invalid value for the "value" parameter. When the value of "operator" is "=" "value" must not be null or empty.

Why is this value recognized as null?

Thank you so much!