Crashlytics on Xamarin.iOS and EXC_BAD_ACCESS/EXC_BREAKPOINT

We've had Crashlytics integrated into our applications for some time now. I did this by using the bindings at https://github.com/Reedyuk/Xamarin-Bindings I also implemented the hook that preserves SIGSEV and SIBGUS actions after Crashlytics is installed to ensure NullReferenceException is catchable.

However, we are getting quite a lot of crashes reported via Crashlytics that start with something like;

EXC_BAD_ACCESS KERN_INVALID_ADDRESS at 0x04efd6c8 or EXC_BREAKPOINT UNKNOWN at 0x0000defe

It is mixed as to the origin, sometimes they are from mono libraries, sometimes iOS SDK libraries and sometimes our code. It is also concerning is that these happen even if we do;

try
{
   // Code that causes EXC_BAD_ACCESS / EXC_BREAKPOINT
}
catch (Exception)
{
   // Do nothing
}

Additionally, they are impossible to reproduce locally, and we are reliant entirely on Crashlytics to tell us about it.