Welcome to the Forum @anon59828738 and thank you for reaching out!
If I understood correctly, you are trying to run an Advanced Search to find the value of a Custom Field, correct?
To find a Custom Field value you just need to follow the steps showed in the screenshot I’m attaching below:
Please note that it is currently not possible to search for a Custom Field that is specific for a Project but only global Custom fields (that belongs to the Organization Library).
Can you please confirm if this is what you are experiencing?
Thank you Peter! Looking forward to your reply!