I don't use Libby as I prefer to read on my eInk kindles vs a tablet or phone. And I don't have any fruit based technology.
That said: I have noticed that when I borrow from the library -- via Amazon if there's a kindle compatible file* -- I can specify which kindles to send it to. When I finish reading it, I can, theoretically, return it to the library direct from the kindle (any of the devices to which it's been sent). When I do, it definitely is removed from that device as well as any other kindle devices I had sent it to. On each device I get a 'letter' that says it's been returned. And it HAS been returned per the Amazon devices and content page, BUT, often, if I go to the library website, it will still show as loaned out to me. Now this isn't a problem for ME. BUT I like to return early if I finish early so that the next person in line can get it sooner. So I try to remember to do that.
If the loan simply expires -- which happens sometimes if it's non-fiction I've borrowed as I find I don't read those as fast -- it will just disappear from the kindles and it's gone from both my Amazon account and the library site shows it's returned. I do generally get an email a couple of days ahead saying that the loan will expire soon.
I suspect borrowing via Libby is a separate operation -- even though it's connected to the same book/library -- and that's why, if you return via Libby, it doesn't register as returned on kindles.
*if the only option is an ePub file, I return the book immediately. I only read on kindle and ePub isn't compatible. Sometimes, with a relatively new release, I know there's a possibility that the publisher will release a kindle file for libraries after it's been out a while. In such cases, it was probably on hold anyway, so I just put it back on hold after returning in the hope that a kindle file will eventually be available. There's nothing I want to read that badly that I can't wait. And if there is NEVER a kindle file available to borrow or at a reasonable price to buy, I'll likely never read it. That's just me: YMMV.
