In case others are facing this problem, just wanted to report that new updates deployed to App Store compiled with Xcode 10.3 (don't know about Xcode 11 yet) are failing when downloaded and run on devices with iOS 10 or earlier (roughly 20% of our users on older iPads). There is no out of memory indication. The crash logs do not indicate any Exec errors or Fatal Exceptions. They just stop at various points in the app (within system libraries) and are random but bunched within 5-6 system libraries. It was fine at the end of last year. Don't know when this started to happen this year.
To eliminate variables, even the same archived bundle created earlier that has been running fine on these machines uploaded again (after changing the two Info.plists inside to bump version numbers) and released after review also fail so it has nothing to do with any code changes or recompiles or configuration changes. Something in the way they are packaged for deployment into the older devices.
The problem does not occur with local debug runs on simulators with those iOS versions.
They all pass review since they are only tested on latest iOS. Users on devices with iOS 11 or later have no problem.
If anyone has faced something similar (not sure how many still support iOS 10 or earlier) or have more insights into this, please post.
