Outline view in explorer doesn't populate, or only partly populates

[Dingotush]

I have been experiencing problems with the explorer outline view either:

• Being empty - No symbols found in file.rpy
• Only partly populating - Some symbols present, others missing

Initially I thought this was down to complexity of my main project, however I also see it in a simple project freshly created with RenPy 7.4.8. (extension version v2.1.7)

define pc = Character("You")


label start:
    show screen simpleDateTime
    pc "Urrgh, Mondays. Who needs them?"

    "You stay in bed, feeling ill."
    $ addPeriod()

    "You manage to eat a little chicken soup, take an aspirin, and go back to bed."
    $ addPeriod(2)

    "You wake and check your socials, but it is all too much, and you let sleep take you again."
    $ addPeriod(3)

    "Wait ... It's lunchtime? How long did I sleep?"
    "No ... this can't be happening. Am I having a lucid dream?"
    $ addPeriod(-6)
    "Your alarm goes off, time to get ready for work."

    "End."
    return

Having read issue #151 I checked that saves\navigation.json is present, and it is. It also contains an entry:

    "label": {
      "start": [
        "game/script.rpy",
        4
      ]
    }

In the same project it only finds two definitions in the unmodified options.rpy (both the preferences ones, but none of the config or gui ones). It also lists them as define rather than default:

Looking at either gui.rpy or screens.rpy shows nothing in the outline.