After completing a couple of unique quest I am then given 2 repeatable quests a blue daily and a pink public quest of the same name from Jeff Issac
These are called 'Massive Guard' and the other 'Experiment Materials'. ( a daily and public quest for each of these 2 quest)
I have entered in Easy mode, Massive Guard recognises the Golem Sentry is dead for the blue daily quest and completes ok, It does not recognise the pink public quest as completed. I have redone the area numerous times, completing the whole instance. I have closed the pink public quest for 'Massive Guard'' and restarted it. still won't complete the public quest on full completion.
The same situation is for 'Eperiment Materials' quest. It completes the blue daily quest ok, but dosn't recognise the Fire Golem death or the Ice Golem death for the pink public quest. Strangely it dose recognise you have picked up the fire and ice energy crystals that are also needed for this quest.
I have not tried both of these quests for the public quest side in Hard Mode, but, if that's the cause they should probably be allowed to complete in Easy Mode also as the case is for the blue daily
Another public quest I havnt tested yet , is called 'More magical feathers', I have completed the blue daily side ok, I am just locked out of the instance at the moment to test the public side. Had to get my thoughts together for the above 2 quest while they were fresh in my mind., but it might be worth checking also. It might be ok as it involves getting a dropped item from the final boss whereas the other 2 were just kills causing the problem.
Cheers