Thanks for replying.
Correct - I have 6 total sites on my WordPress installation, but when viewing each site via WPTouch, the 'home' link directs to the Network's main site.
In one case I specified a page, rather than "WordPress Settings", in the "Home Page Re-Direction" area of the settings, and that worked as planned. So I'm fairly certain that the plugin was active on the subsite(s) directly.
Separate issue, but may be related...
When the plugin is active and I click Mobile Theme "off" at the bottom while on the Main site of the network, it continues to display the mobile site. However, on any of my other sites when I click "off" it tries to send me to the URL using https:// and "a secure connection cannot be established." Perhaps this can aid in helping me find a solution, or perhaps it's a different problem entirely.
Thanks again for taking the time to respond to the comments here!