Wireshark let me find out that Unity's WWW class ignored request HTTP headers on iOS, causing our usage of S3 to fail. I worked around the problem by switching to URI based authentication.
On-screen keyboards displayed Chinese after visiting a system menu. We freed the async operation when the system menu "canceled" the keyboard operation (it wasn't supposed to be even displaying), but apparently the system had a use-after-free bug. I worked around the problem by switching to a 4 entry LRU allocator, keeping the past 3 or 4 canceled operations around untouched (1 would've probably sufficed, but I'm paranoid.)
A WinRT API to check internet connectivity would exit(3) our app without error messages or related callstacks - but only if the Charm bar was open for more than 10 seconds, assuming you called it once per frame on the main thread. I had to bisect our history to figure that one out - and repro in a new test app to confirm it was the real cause.
EDIT: Third party injected DLLs crashed our app at least twice - once for some monitoring software on a coworker's computer (crashed when closing file handles as build tools tried to clean up and exit), once for an old Microsoft Word IME that predated the Win8 app sandbox who's restrictions it was violating. The monitoring software was uninstalled, the IME I couldn't think of a reasonable workaround for and left to Microsoft to fix.
On-screen keyboards displayed Chinese after visiting a system menu. We freed the async operation when the system menu "canceled" the keyboard operation (it wasn't supposed to be even displaying), but apparently the system had a use-after-free bug. I worked around the problem by switching to a 4 entry LRU allocator, keeping the past 3 or 4 canceled operations around untouched (1 would've probably sufficed, but I'm paranoid.)
A WinRT API to check internet connectivity would exit(3) our app without error messages or related callstacks - but only if the Charm bar was open for more than 10 seconds, assuming you called it once per frame on the main thread. I had to bisect our history to figure that one out - and repro in a new test app to confirm it was the real cause.
EDIT: Third party injected DLLs crashed our app at least twice - once for some monitoring software on a coworker's computer (crashed when closing file handles as build tools tried to clean up and exit), once for an old Microsoft Word IME that predated the Win8 app sandbox who's restrictions it was violating. The monitoring software was uninstalled, the IME I couldn't think of a reasonable workaround for and left to Microsoft to fix.