Why would my CocoaPods-infused Xcode build never complete, citing "Canceled" rather than "Failed" or "Success"?

Question

I'm getting the above message every time I try to build, no matter how (Pressing the ▶ button, ⌘B, ⌘⇧R, ⌘R, Product ❯ Run, Product ❯ Build For ❯ Running), it seems to otherwise succeed, but instead it says "Canceled". It never runs (even ⌘⌃R won't run it - I get a dialog that says "The file “[censored].app” couldn’t be opened because you don’t have permission …").

I suspect this is related to me trying to introduce these into the project:

• CocoaPods
• A pre-build script which installs/updates the pods

In the build log, everything succeeds (with some minor code-level warnings like deprecations), and then there's this:

I looked to see if my script was doing anything weird, but as far as I can tell, it does everything it's supposed to and then exist with code 0.

I did make sure that I am not manually canceling it. I'm not placing the cursor near the ◽️ button, I'm not pressing ⌘., nothing. I even pressed run and stepped back from the machine - it still does this.

I restarted Xcode, I cleared DerivedData, I ran pod deintegrate; pod install; pod update, I even installed OS updates and restarted the machine. It still does this.

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Update

I commented out all the lines of the build script and the build succeeded. After that, I slowly reintroduced them until I found that these lines are the culprits:

pod install
pod update

If I comment out both, it builds. If I leave either or both, it Cancels. I've confirmed that both return a status code of 0. I don't know what side-effect of these causes Xcode to Cancel the build nor how to stop it, but I know it's in there.