A breakpoint set on that line with showModal() for .failure is executed but I do not see the popup that I was expecting but another one. Ok, working on it....

I assume that you integrate both of these results into your model on the main thread — because that’s the only place it’s safe to call reloadData() -> Exactly. I will try to catch the error when it occurs next time and post the crash report. As I said it doesn't happen often.