This functionality doesn’t seem to work in my tests. I have 12.9.7 and the Knowledge Base task list page works as described but in my own collection the interactive checkboxes are not rendered.
Is there a collection setting / requirement needed for this to function?
I think there must be something corrupt in the collection that i was using to test. Just noticed that it also wasn’t picking up some custom css that i had added to the Display settings.
Added the checkbox markdown to a different collection and all was as it should be.