Help wanted: I want the experience I should have gotten.
Resolution: none yet.
Need: appropriate customer service for Blizzard to make right the results of a glitch or mistake by its employees.
While waiting (you can see from the time stamp for this post, and from the comments how long I've been waiting for service) I've learned the following things.
First, if you have any sort of ticket in and a GM does something for you, and your XP bar turns off, it is not a display glitch. Do not waste time trying to figure out what has gone wrong with your UI.
In my case, I fell off of the dirigible. I put in a ticket and the GM was kind enough to put me right next to the portal and explain where the portal back to the gunship was (I had hit featherfall, drifted into the alliance camp, and, well, you know, got far afield).
But, from that point on, I did not earn any experience. Did not realize it because the quests said I would get experience for completing them, but the bar didn't show. Figured it was a UI issue. Finally figured out why my bar wasn't working after every tweak I could make to my UI (which is plain) and everything else -- experience was turned off. Figured out when it was turned off happened by looking at the amount of experience I had (just enough to get into the problem I had when I got the help).
So, the problem was I had finished all the quests in the zone and all the bread crumbs lead to quests that require a minimum of 86. I explored, zipped down the tunnel, tried to climb the stairs to the archeology turn in (turns out you need to be 90 with flying to reach it), etc.
Anyway, if you are DPS with 45 minute ques who usually plays 30 minutes at a time, you can't dungeon your way to 86.
But, two things.
First, daily quests will level up cooking and fishing for you.
Second ... if you explore the right way (which I failed to do the first time around) you can find the location for the cooking trainer. They have quests available at level 85! More dailies.
So, you can do dailies to 86. Not perfect, but better than being locked out.
Oh, and if you get help from a GM and your experience bar disappears, go to the web, do a search and find the guys who turn it on and off. Hit them up, pay the 10 gold, and you are back to life.