Elasticsearch/Kibana Upgrade Assistant only showing . indices

Question

I am upgrading ES/K from 5.6 to 6 and then 7. I am looking at Upgrade Assistant to help with breaking changes, but it doesn't seem to pick up indices that contain the said breaking changes. I've deliberately created multiple type index to see what a 5->6 failure would look like.

There are obviously other ways to check (api reindex etc), but I would like to understand why the UA isn't showing potential breakage (yes, after reboots, cluster refresh etc) - is there a setting/action I need to preform for them to be picked up?

Thank you!