Enabled experiment stopped getting picked up by the analyzer

Question

I'm running Dart 2.8.0-dev.18.0 and I want to use non-nullable types. That's why I added the following to analysis_options.yaml:

analyzer:
  enable-experiment:
    - non-nullable

Everything worked fine until it mysteriously stopped working when I turned on my computer again. No matter what I do now, I get a message saying This requires the 'non-nullable' experiment to be enabled.

This is a pure Dart app.

Also, when I open up Analysis Server Diagnostics, I see that the "non-nullable" feature is enabled in the Contexts tab.

Answer 1

After much despair, the age-old advice of "delete the .dart-tool folder" proved to be correct.