Yep, started happening yesterday for me. But not just for logging. It’s any time I hit a load screen of any kind.
Every time I come out of a loading screen, teleport, cutscene, or log in my quest tracker is empty and I have to manually select my quests to track again.
Having same issue and spent like 1.5 hours trying to figure it out. I am somewhat relieved it is not just me!
Been having the same issue since yesterday’s hotfixes.
Yup. All gone, though not on all chars.
Same timing for me.
A Blizzard employee over in Customer Service is suggesting that people may not be doing their UI resets correctly. Since we have addon authors and UI/macro experts posting here, I would have to disagree with his suggestion.
I backed up and then deleted the WTF, Cache and Interface folders. I logged into a character that has been impacted by this, opened the quest log, tracked the quests, exited game, logged back in and the quests had been cleared.
This would suggest that this is a game issue and not a player issue.
I agree, this is a Blizz issue, I spent hours last night playing with this. What happens at either logout or login the Quests get reverted back to Track. All I can figure is that is some sort of default in some rountine got accidentally back in. The state Track/Untrack always reverts back to Track.
Still happening. Just logged in and no quests.
Did everything everyone suggests. Not fixed.
I am also having this issue on my characters. Blew up all the addons and tried all the console commands just like above. Fingers crossed for a fix soon™.
Same problem here.
happening to me too.
got the same thing here on all my toons
I am also having this issue. I played yesterday evening without issue with the quest log and quest tracking but I logged in this afternoon and anytime I log in my quest tracking is gone
Happening to me as well.
Could it be something to do with the newly introduced transmog tracking system that is causing this?
Bug is happening to me as well.
Has anyone tried unplugging their character and plugging it back in?
having the same issue, on top of it I can’t seem to collect the aiding the accord weekly in val and it no longer shows story progress in the quest log
I’m experiencing this bug as well 
Hopefully we a get a blue post soon
Same is happening to me.