Split screen not working for IPad Air 2

Thinking about it, mine stopped working after I installed updates to a bunch of third-party apps and tried using those. I think that's pretty telling…

I wonder if one of them got stuck. As I said, I wish I could remember what I tried. I’d deinstall it to see if that got the sliding panel back.

Anyway, I’m glad I’m not alone. Hope a fix comes soon. Meantime, if you’re not a developer, all we have is: http://www.apple.com/feedback/iphone.html

thanks for the tip, will try that!

So mine's working again. I went into the task switcher and swiped up every app, then force-rebooted the iPad (i.e. home/sleep until it reset). On wake, all the apps were still in the task switcher, so I quit them again. I opened Notes and dragged from the right. Only the tab appeared. But then I dragged again from near the home button and it worked.

My assumption now is that something gummed up the feature somehow, and that the tab thing is a separate process somehow, to make you drag from the 'correct' point. Only dragging from there does nothing it if gets stuck. I suspect (although have no proof of this) that Pixelmator might have been to blame, because it has support but also happens to be such a resource-hungry app. (On an iPad Air, it sometimes can't open, due to RAM requirements.)

Well, I gave that a try, following your procedure to the letter (several times), but no luck. I don’t have Pixelmator, so if there's a "stuck" app, it's not that one in my case.

Tweetbot!

Okay I can't honestly blame Tweetbot, but that's the app that gummed up slide over on my iPad. I was reading an article about how great the new Tweetbot is, and I realized that I hadn't really taken the time to peruse it. Back out to springboard, and I see that the Tweetbot icon is dimmed, as if it's in the middle of an update. But it's not. And not only that, I can't delete it, even after a restart. So I log out of my Apple Store account, and that unsticks it. As I'm redownloading Tweetbot it occurs to me that that's the last app I tried in slide over.

Now, with all my apps unstuck, slide over is working as it should. I still don’t know how my apps decided to get stuck in the first place, but let it be known that a stuck app may very well take slide over down with it. And, as we suspected above, deleting the app that took down slide over seems to be the solution.

It only works if the App on the left supports split view.