Create new Backend from Product context does not allow IP in private base URL

When creating Backend from product context: Product > Integration > Backends > create new Backend (`/apiconfig/services/#service_id/backend_usages/new#context-menu`), "Private Base URL" field does not accept IP address. When IP address is entered, the Create button remains inactive.
Create Backend page (`/p/admin/backend_apis/new`) works as expected.

Example:
When using httpbin as private base URL http://httpbin.org:80 works as expected but http://54.156.165.4:80 does not