Ran into this similar issue, funnily enough: While trying to open the Secret Cache containing the "Untested Speed Serum", I was attacked by a Choya right as the action was completing. The dialogue window didn't pop up at all (where I would've clicked "Hold on, Petey" and completed that part of the collectible. I've tried logging off/on, and using a different character to complete the task, but no such luck. Submitted a bug report, And contacted gw2 support. Support stated they couldn't help with resetting anything and suggested I try a different map instance and/or wait for the daily reset. Daily reset has happened, and no changes noted. I'm still on the same map (ip is .17), so I'll update if I get a different map.