Duty Finder timer until allowed to reque keeps resetting

[Vespar]

This is the second or third time this has happened to me in a few weeks. I don't drop DF parties often unless people are belligerent, so it might be happening more than I know. But I can recreate the issue EVERY time I zone after leaving a DF party mid-run and take the 15min debuff. (Or should I say 15min plus...)