How to find the call site for incomplete completions in a stopped app?

I am fixing bugs / extending a macOS app written by somebody else in Swift. I’ve made changes to it and debugging it, so breakpoints/rebuilding/debug print/change/rerun it isn’t a problem.

But it is a multi-threaded, async app, and when I pause the running app, it will not display source code location in each thread where it is. I only get assembly. [and, yes, "Always Show Assembly" in OFF]

It is inherent to async apps and threading that they spend most of their time waiting for the user to do something. Hence if you stop an app, you’ll almost always be in system code somewhere. But I think wanting to see the origin of completions that are pending is a legitimate question for somebody debugging (and trying to understand how the app works).

Am I not aware some feature in Xcode / LLDB to reveal this?

How to find the call site for incomplete completions in a stopped app?
 
 
Q