Podcasts no longer auto-downloading under iOS8

Question

Sometime around iOS6, Apple changed the behaviour of the Podcasts app. Instead of having to open the app to check for new episodes it would, if suitably configured, download new episodes in the background.
iOS8 seems to have broken this feature. Since upgrading my 4S, Podcasts will notify me (via the badge) that new episodes are available but will not begin to download them until the app itself is launched. All of my settings are as you would expect; automatic downloads are on, downloads over 3G are on just in case I lose WiFi, check time is 1 hour, Background App Refresh is enabled. But after an arbitrary time running in the background the Podcasts app will just stop fetching new episodes, until it's launched again.
I used to be able to go to work in the morning safe in the knowledge that my new episodes were downloaded and waiting to be played. Now I have to remember to launch the Podcasts app at least five minutes before I leave the house, to be certain of downloading anything that was updated during the night. This is a huge step backwards.
The behaviour can be mitigated to a certain extent by making sure Podcasts is the last app to be launched before putting the iPhone to sleep at night. But it's still no guarantee, because the app's background processes still seem to die after a couple of hours. I see similar behaviour on my 4th generation iPad but anecdotal evidence so far suggests that the Podcasts app is not being shut down as frequently on the iPad as on the 4S. All of which suggests it's a resource issue, the iPad having more RAM and more efficient hardware than the 4S.
Reading some developer blogs there is vague information about a new feature in iOS8 that automatically kills "battery hungry" apps. But of course Apple are notoriously tight-lipped about the inner workings of their operating systems and so far I've not managed to find any information on how this feature operates, what its criteria might be for determining what constitutes a "battery hungry" app, or even whether it actually got implemented. What's interesting is that, looking in the new Battery Usage page of iOS8 on the 4S, Podcasts is nearly always at the top of that list with up to 44% usage in a given period. But this is hardly surprising as I listen to podcasts most of the working day with the phone in Airplane Mode.
Might this new iOS8 feature be so aggressively determined to kill hungry processes that it's crippling Apple's own built-in app's ability to do background downloads? I'm not a developer, so I don't have access to logs or any other useful debugging tools and this is a guess based on pure gut and experience. But something definitely seems to have changed in iOS8 and if Apple did introduce a battery-saving feature that kills background processes then it will be a staggering coincidence if the two things are unrelated.
If anyone else has seen this behaviour can you please add a comment with any ideas or interpretations you might have, or at least click the "I have this problem too" button. I intend to contact Apple directly (or as directly as is possible with Apple) and it would be nice to be able to point to a group of people with similar issues rather than just my lone voice in the wilderness.

Answer 1

Hmm. It looks as though I may have jumped the gun on this one.
A couple of days after posting the first reply I awoke to find that, of two podcasts that should have downloaded overnight, only one had actually downloaded. The other was flagged as new when I woke the phone but only began downloading when I opened the Podcasts app. I put this down to a possible feed problem and ignored it.
But over the next couple of days the pattern repeated. Some podcasts were downloading automatically while others weren't, especially overnight.
I'm not a developer but I am in communication with one, and he has demonstrated that there seems to be a new function in iOS8 that will kill certain background processes after almost exactly four hours of uptime. I have been able to see this first hand by looking at his app's log files.
Alas there are no such log files for the built-in Podcasts app, or at least not any available to the general user, so I can't know for certain whether this is what's happening here. But it definitely feels as though something might be timing out over longer periods than was happening before.
I need to do some more experimentation but here's what I think has happened here based on my experience and the vaguest of information from this blog post.
iOS8.0 introduced a couple of new battery saving features designed to curb the activities of "battery hungry" apps. The first of these features closed background apps at indeterminate intervals when they were perceived to be draining power, while the second killed any long-term background app after approximately four hours of uptime regardless of what it was doing.
The native Podcasts app accidentally fell foul of both of these new features, meaning its background downloading of subscribed podcasts was rendered almost useless.
iOS8.1 has changed things so that the "battery hungry" algorithm is less aggressive and no longer closes the Podcasts app. But the four hour timeout is still being applied, meaning that the Podcasts app will only do background downloads for a maximum of four hours before it needs restarting.
As I say, this is pure speculation but it certainly fits in with my experiences, the experiences of the developer I've spoken to, and what's written in that blog post regarding power management. I need to do some timed experiments to be certain, which may take a while, but it definitely feels as though only one of the issues has been fixed with this update.
I'm going to start by leaving the phone on continuously with the Podcasts app front and centre when I'm not using anything else. If my theory is correct, there should be no missed downloads because the four hour timeout won't get a chance to kick in. It's less than ideal because it's trying to prove a negative, but it's the best I can do.
More news as it comes.