That's right @dnutan. Exactly what I saw. So I reached out to the maintener of the app and he's suggesting I use the occ command to add it. But it would seem I need to update the info.xml version info.
Problem is though the Nextcloud version listed in info.xml looks correct:
nextcloud min-version="9" max-version="11.9"
So I did a check of what version I have in Nextcloud:
sudo -u apache /usr/bin/php /var/www/html/nextcloud/occ -V
And I get:
So I'm definitely within the min/max listed in info.xml.
I'm stuck? What is the problem with the version in info.xml that is causing this to not work?