So I encountered a bug while collecting "Dragon Hearts" for Bahamut skill. During the quest I obtained more Dragon hearts then required for that particular quest. I managed to pick up 55 while there was only 25 needed to complete the quest. In a guide made by: "Plenty". The person describes that you need in total 150 Dragon stones in order to complete all the quests for Bahamut 0-30. I was going to strive for 150 Dragon Hearts but stopped at 55, once I finished that quest. I started the next one hoping to instantly complete it. Unfortunantly I had to get 0/30 dragon hearts again and I already had 31 in my inventory. Let me demonstrate this with a GIF: https://gyazo.com/2a5732554346a949e43397fa09397626
Dragon hearts for the Bahamian quest line are unique to the individual quest that you are farming. You will find that different hearts from different parts of the quest do not stack and I believe this is an intended effect rather than a farming bug.
Quite a few quest ETCs are coded in this manner, hence not possible to farm in advance The Dragon Hearts could be Dragon Hearts [1], Dragon Hearts [2], Dragon Hearts [3] but we're unable to see it Just an example
The actual bug is that quest items should no longer appear as drops once you have reached the required item count for the quest. I believe this is reported already.
This is an issue. Once I read the guide on how to gain Bahamut. I understood it as to complete all the quests you are required 150 hearts. Which I was striving for. Yet I did not do that because of lazyness. However this is something that should've not occured, I should've been able to complete this without this unknown issue.