If a model and its children are "_isOptional": true and set to use a trickle button, the model does not mark as _isComplete because the trickle button is not visually available to be completed.

Whilst the JSON is unlikely to be configured this way whilst authoring, it is possible when using a role selector or diagnostic type plugin which can dynamically update _isOptional depending on user choices.

This can be resolved by excluding non-trackable components such as the trickle button from:

It might be useful to create an API method returning these models so it can be used elsewhere as required:

return this.getAvailableChildModels().filter(child => child.get('_isTrackable') !== false);