Nevermind. I have multiple user logins for my network of WP sites, and the user I was using to login to my sub-site did not have sufficient rights to view this plug-in. Not sure why, but when I logged in with a “Super Admin” to my sub-site, the plug-in showed up in the list.
I guess this is a good confirmation that the plug-in is in fact compatible with multi-network WP sites.
