Dear Jota (By the way, I’m from spain and we can speak spanish if you prefer)
I’m not able to add functions.
Tried to add functions to custom service “Test” and got error 500 after click on “add functions”
You can observe in my pictures that steps are OK.
I’ve added you an admin account to my site “https://lms.manuelangel.es”, user “XXXXX”, Pwd “XXXXX”.
I authorize you to connect to check this issue.