Hello, I'm one of those mad/annoyed by small problems here and there.
I have a 2015 F150 Lariat with the pano sunroof. As many owners experienced, my sunroof rails broke and got them fixed by a dealer luckily under the extended warranty. Now it's out of warranty, and there's a 1.5" gap in the back between sunroof sunshade and headliner. I've searched for weeks, and there are a ton of information on the sunroof but I have yet to find information like youtube/assembly diagram for the sunshade.

Anyone experienced this issue? There appears to be a long tensioner that is loose on top of the shade in the back but can't figure out how to put it back firmly. I'm assuming that is the issue. It's really hard to see without removing the back sunroof glass. Any tips/info appreciated!

 

Right in the middle is one of the strong magnets that hold it to the frame. Have you pushed up in the middle? You will hear a snap. What happened to me on my '16, when I was installing the factory antennae for the TCU, the magnet broke loose from the headliner and stayed stuck to the frame, So I had to pop it off, rough up the back, and a put little JB Weld and is good as new. this could have happened on yours.
Though I doubt seriously they were pulling your headliner down. Pull it down a little after you unsnap the corners, shine a light in there and see what going on. The magnets are smaller than nickel.

 

They probably did pull the headliner down in back, to drop the motor and line up the guides if they were out of sync.

And the magnet might have pulled out of its mounting boss. Just pull it down and see if the magnet is stuck to the track and not attached to the headliner boss.
Pull it loose and reinstall it if it is. If not, might be like the previous suggestion that the boss has come loose from the headliner, but that's not super likely. It certainly wouldn't just fall off and bow down like that unless someone pulled it down.

Edit: Okay, I just re-read your post. Is the piece you're talking about that's loose back there a long skinny metal piece? If so, that MUST be reinstalled or the shade will pull loose from the sides. I will post a video of it being done out of the track so you can see how it's supposed to fit, but if they didn't install it right, they should fix it.
And there's no possible reason for that to be off unless you got an entire new track replacement. Which is what you should have gotten anyway, since there's just about no way that the upper guides breaking on a 15 don't take out the lower cable guides as well, not at this point. They all need a track if they took this long to break.

Here's the video, hope this isn't actually what's wrong, but from your description I'm not sure what else it could be. Jump to 29:53 for the part I'm talking about

 

Wow, this is the video I've been looking for!
Yes, that skinny metal piece came off. Hopefully, snapping back in fixes the problem. My dealer is an ********, won't take it back to fix it.
Much appreciated!

 

just be careful. It's harder to get to with the track in the truck. And if you snap off those little tabs that it attaches to on the ends, the only way you can get them is with a new track

 

I wouldn't have left the dealership with it that way.

 

You are right. Had I noticed it at the dealership, I wouldn't have either. With my infant and toddler in the back, running errands, I was too distracted and just drove off the dealer lot quickly, but only to find the issue days later.

 

Just curious, it's not the headliner sagging in the middle from a disengaged magnet in the middle , it's the shade sucked up in the middle caused by the shade rod shown in the above how to connect shade rod section of the video?

 

I haven't got a chance to put that long metal piece back in, but are you saying that there's the magnet inside of the headliner in the middle that should engage to that metal piece? I'm planning to work on it tomorrow and will find out.

 

No, the magnets are just what hold the headliner up.