How do I fix these path corners?

https://forums.adobe.com/people/Barbara+Ash  wrote The reason they didn't look right at first even though you lined up the end points, is because Illustrator defaults to putting the stroke half inside and half outside the path, like this: (EDIT)

The only problem I found with this solution was that, while it DID make the corner look like a rounded closed corner, it only affected the one corner. The other corners in my path remained pointed (even if the entire shape/path is selected).

https://forums.adobe.com/people/pixxxel+schubser  wrote These are single lines. You have to join them. Use the Sharpener tool  or select both intersecting anchor points with the white arrow and [Strg]+ (that means Object --> Path --> Join)  or select both intersecting anchor points with the white arrow and use the icon in the Control bar Have fun

This was the best solution. Thank you and apologies for the late reply. Been a crazy week at work.

https://forums.adobe.com/people/Monika+Gause  wrote Looks like those paths are not joined.

Interesting enough, when I selected all, then Joined, the corners healed themselves. So you might have been right. Although I don't fully understand why they looked so bad earlier. The path points intersected, with a snap.