Delete stage not reflected in UI

Have defined a plan that has 3 stages, with the 3rd stage being defined as "manual". For the 3rd stage, I only created the stage, but no jobs in it (I was still thinking how to organize the build). Eventually, a day later, I decided to remove that 3rd stage in favor of creating a new plan. When I went to delete the stage, after pressing "Confirm", the UI returned showing the stage was still there. When attempting to delete it again, received error message saying that the stage does not exist.

Hitting Refresh in the browser while on the plan configuration page was still stubbornly showing the deleted stage.