It's not working for me, either.
I can add it, then click Save. The house number button bar disappears, then it just sits there. If I click away from the house number box I get the unsaved changes popup.
After a while I get the "An error occurred while saving. Please try again." response.
Perhaps try deleting and rebuilding the segment?
Waze Global Champ, Country Coordinator
Country Manager: Canada
Area Manager: Edmonton, AB; Prince George, BC; Maui, HI; Georgetown, KY and various places in between