Why are breakpoints in Visual Code treated differently depending on how the file was opened?

A breakpoint in my Mocha test works when set in one tab, but not in another.

I figured out that if you do File->Open, then the full path appears in the tab, and breakpoints work. (Second item in screenshot.)

But if you open it from the Explorer or Find views (first item in screenshot above), which is a more natural way to access a file, the full path does not appear, and breakpoints all become Unverified (gray) during execution.

How can I avoid this while still opening files in the normal way?

from Why are breakpoints in Visual Code treated differently depending on how the file was opened?