I'm using an Android 5.x Moto E 2nd gen / 2015. I'm using the Gmail app. When I select text in it (well, when I try to select text, don't get me started...) and then press the "search" magnifying glass icon at the top right of the display, I get a tab/sheet for the search. And it turns out that the sheet doesn't appear in the "show all tabs" / "recent apps" list. At all. Ever. No matter what. As far as I can tell. So once I've lost it by going to some other app, I've lost whatever work I was doing hunting through the web from that search. So, like, that's kind of annoyingly stupid ux?!

While I'm on the subject, I'll mention that the ordering of the tabs/sheets in the recent apps list is not a good UX for me. Several times I've closed the wrong things due to how animations moved tabs around. And the gestalt around "which tab I was just looking at full screen" / which app I was using is not good. For example, if I'm shopping craigslist for a bargain on a sewing machine (real world use case) I open a bunch of tabs. As I try to look at each one, it is hard to know which ones I've already looked at, and which I haven't.

There's a buhzillion other things about Android 5 that drive me batty, too. I'm trying to just let go, let go, let go right now... ;-P