I commented on another thread - https://forums.xamarin.com/discussion/57179/uwp-immediate-crash-in-release-mode - and then realised it had an accepted answer, so may not get looked at as a result, so raising a new thread for this issue. The "accepted answer" for the other thread doesn't work for me (the only thing I haven't tried, from the whole thread in fact, is adding assemblies per some quoted links which are now no longer valid). Even trying it in debug mode doesn't work. App works fine in both Debug and Release in VS,but when I create an app package and try it from there the app crashes after starting, with
"Faulting module name: Windows.UI.Xaml.dll, version: 10.0.17763.404, time stamp: 0x5c3c199a
Exception code: 0xc000027b
Fault offset: 0x008dc0f1
Faulting process id: 0x1a64"