Following the new Jakata release I’ve noticied that some instances does not show Knowledge results when opening a new Incident.
The solution is quite simple.
Open the Form Designer, and find the Field (In the Field search bar) Contextual Search Results (formatter). Place this under your description field, and you should be good to go.
On my instance it looks like this:
Note that this error could be an issue created by ServiceNow, and could also be solved by creating a ticket with them.