Changing labels via REST api doesn't refresh configuration in the web UI

Steps to reproduce:
1) use REST api to add a 'test' label to a plan (that has no such label)
1a) in the UI the plan won't be displaying 'test' label
1b) while I'd expect it will
1c) note the label was added to the db table buildresultsummary_label
2) edit configuration of that plan and save it (for example changed the plan name from "Plan name" to "Plan name2")
3) observe the label appeared in the UI