I can't find a forum more suitable for this that I'm able to post in, so I thought I'd post it here.
There are several PVE quests (including those noted in the topic heading above), that commonly become bugged for players who complete them solo. I combed the knowledge base for answers and discovered some dev/gm responses that explain that the quests are "meant to be done in a group."
Now I have no problem with group quests, but if the side effect of performing them solo is that they're going to become bugged, then I think they need to be labeled as such. Otherwise, it's an immense source of frustration for players who find creative ways to complete a seemingly hard quest solo, but who then learn that their work is for naught because the quest becomes bugged.
Otherwise, I've really been enjoying the PVE content in the game
Note: For those of you who have found yourself in this predicament, I've found that abandoning the quests, relogging, and then completing it again in a group works as a solution (most of the time at least).