Issue in n8n reference in variable selector!

Hi dear @jan
according below image:

As you see reference that system make it is wrong and the result is not found.
I myself test some Expressions and found that there are valid one.

You think it is because of my mistake or for system issue .
Best regards

Thanks a lot. That looks like a bug. I will add it to my list.

you’re welcome.
You are a good man.