Problem adding new attributes to existing Asset Type in Centra Site paid edition 9.10

Using CS Control UI
I’m trying to customize REST Service type to add my own attributes, but the “wizard” that come up to edit Asset type has “Add attribute…” button disabled. I’m logged as Administrator.
I attach picture of the problem.

Any suggestion or work around on customizing REST Service type?
Don’t see any options with inheritance from OTB REST Service either…
Thank you

Rest is a subtype of the Service asset type. To add attributes, you have to add them to the base type (Service).

Thank you, that worked.