As of the Pre-Patch of 11.0, this quest can no longer be finished, as the Beacon no longer spawns.
This is missing. Talking to the NPC will bring you to the Vindicar and lets you view the NPCs talking, however since the mission to use the Lightforged Beacon was not fulfilled, one is stuck there.
I tried abandoning and retaking the quest and it didnt help. I cant unlock the allied race because this quest cant be completed.
I talked to a bunch of other people there with the same problem.
Youre not alone. GM told me I was doing something wrong. Still not working. I see the beacon pop up behind the embassy for a couple seconds before disappearing.
I am having the same issue 
A buddy and I are having the same issue, tried to complete it a few hours ago…Thought I was missing something, and was getting annoyed trying to figure it out. I should have checked forums first…woulda saved a lot of time :(. will be submitting a ticket so they know more players are encountering the issue. there is a crystal in your bag you get from the first quest to get to the ship, however later down the chain it tells us to do the same thing and we are stumped. I even attempted to make a portal to dalaran and get to the ship another way and nothing happened for us
I am experiencing the same issue. I was able to do the entirety of the quest but am still stuck on “The Lightforged” Embassy Beacon issue as well.
Same. Can’t even submit a ticket though because when I go to select “Quest and Achievement” category in support, the page just goes blank and I can’t select anything.
Same here was hoping to get one of each allied race to 70 using Remix. Sad that the coolest looking race i might not be able to.
Tried different characters, disabling all addons, two seperate level characters, finishing all other allied races first. Going to Vindicaar manually. Nothing works.
Quest is broken. Beacon must be accessed to complete quest and it does not appear.
Can confirm that after today’s patch (July 30th) still bugged. 
Still bugged for me as well… couldn’t figure out how to open a ticket but I’m sure they know about it by now.
still no beacon. tried everything i can and got a response from CS:
Please rest assured that your concerns have been forwarded to our World of Warcraft development team. They are currently investigating the matter to ensure a timely resolution. While Game Masters like myself are unable to directly fix in-game mechanics, we are committed to supporting you through this process.
i thought they used to be able to complete and restart quest, set account flags and so on. guess they are just AI now and forward everything to dev.
Same issue here, but tracking the objective the marker says its around 77 yds below ground. Anyone got a shovel :-/
update. it was resolved for me. after the second cs response they said it was not working as intended and would be fixed at some point. however when i logged in i did see the beacon now 140yrds behind the building and was able to complete the quest line with it.
Quest is now working for me. 8-3-24
What beacon? There’s no beacon!! This is just stupid.