I am working on the Build your Knowledge Base Module of the Knowledge Basics Trailhead.

What could the possible reasons be for a published article to not show in the Knowledge Tab.  I see the article as published in the Article Management Tab but when I move to the Knowledge Tab, nothing appears (and I am not able to complete the challenge)

I have gone through the steps and checked spelling/spacing on the Article Type.

So maybe I'm missing something here, but I was working through the Create and Customize List Views section of the Lightning Experience Customization and the Challenge section is missing. I tried logging out, then back in and checked several browsers with no luck. Anyone else experience this problem. Here's a screenshot:

Cant finish, geting the error Challenge Not yet complete... here's what's wrong: 
Could not find the published Knowledge article.   but its done