I think Guest David Wain commented there was no way to track down the source of conflicting or unknown keyboard shortcuts on Mac OS.
ShortcutDetective is useful for this task - freeware at http://www.irradiatedsoftware.com/labs/
A more sophisticated App is available for $10 - ShortStop - https://mizage.com/shortstop/
God, the HOURS I’ve wasted trying to find the rogue shortcuts… The fact that this is easy enough to do that it’s available as a freeware app, yet not available somewhere in the OS actually makes me a little angry.
These are interesting (I’ve used ShortcutDetective). What I really want to know is what I assume macOS knows: where is the global shortcut database that triggers macOS stored? It’s got to be somewhere (or multiple someplaces) that macOS has access to so that it can take action based on the shortcut.
I’ve been looking for a way to inspect all the shortcuts that macOS knows about so that I can use that guidance for configuring my own. I frequently run into conflicts, and I don’t find apps like ShortcutDetective, or KeyCue, 100% useful for identifying conflicts.
Here’s an explanation and a potential way to see (many of) the shortcuts. There is no global file, just keyboard events the system processes without knowing whether they will do anything.
Thanks. Yes, I had mentioned KeyCue above, and I own it. It’s cute but useless for identifying conflicts, in my experience.
I suppose I’m just ignorant 
Yikes. 6 years since the last update. Doesn’t exactly overwhelm you with positive feelings about the app’s future.
(I actually wonder if it’s feature-set pre-dates sandboxing which is how it works, but can’t be updated because Apple wouldn’t allow it under the current rules.)
Yoda might say something like “Ignorant not you are.”