how is the automatic upload supposed to work ? i have it enabled, but have never seen the app start the upload automatically - the opposite, it tends to stop the upload every now and then…
Sorry for the late reply! Been travelling and been sick.
It uses the background mode fetch, which isn’t a pure real-time background execution and is meant for checking and downloading data now and then (like email I guess). When the system thinks it’s a good idea to run background tasks for a while, it invokes the app for a short amount of time. If you have photos to upload, and background upload enabled, and have WiFi, it will upload photos, for as long as the system will allow it.
If you are interested, you can read more about how backgrund tasks work on iOS and it’s limitations: Apple Developer Documentation
It’s far from perfect. If you have slowish network it might not even be able to upload a single photo. I haven’t checked how many images get uploaded on average in each burst, but I suspect it’s not a lot. So maybe it should be removed all together in that case.
I think it’s a better idea to start the upload normally and minimize the app if you need your phone for something else, seems to work pretty good.
hmm. don’t think i got an email about this reply 
i would really love to have proper background upload, but i understand that iphone might have limitations on that.
when you say “start the upload normally and minimize the app”, what exactly do you mean ? if i start the upload and lock the phone, the upload stops (and quite often the mapillary app crashes)
Ah sorry, I mean that you press the home button without locking your phone. Eventually the system will shut down the app, which you may experience as a crash.
oh, but the benefit of locking the phone is saving power and being able to put it in a pocket while the upload still happens.
is that a limitation of ios then ?
I’m not sure, I need to look into this better. I know some apps still run when the phone is locked, like https://itunes.apple.com/en/app/sleep-cycle-alarm-clock/id320606217?mt=8
Maybe it requires that your phone is connected to a charger to work, dunno. But I’ll look into it soon hopefully!
in several cases i had left the app in the background, returned to it a bit later, navigated around a bit - and then it either closed or crashed.
that would seem more like a crash, not system-enforced closure, right ?
i’d assume that system wouldn’t close an app that i interact with.