"Sorry, unfortunately I didn't find any Sermons" after update.

Ok, I think you set me on a path that fixed it.
I have lots of menus. I went through every menu to find all items that point to SermonSpeaker. 

I found a less-used menu item that points to the series page, with the selected category set to uncategorized.
I set this to Sermons, and the series page I was using started to work. Then I noticed that other menu items pointing to specific series were also set to uncategorized.  Setting each of these resolved their respective categories.

It seems like before, it worked fine if the list's pages were set to uncategorized. But now they need to be explicitly set.
Not sure if this was a SS7 or a J6 change.

I appreciate your help.

Hehe, so it was both related to menuitems and categories

I think it may be caused by how Joomla is building and parsing URLs. SermonSpeaker 6 did still use some own rules and with SermonSpeaker 7 and the namespaced code, I could finally let Joomla do the heavy work. Your issue was a sideeffect of it apparently. Joomla is more restrictive than SermonSpeaker was.