I'm not entirely sure there's a solution for this as I don't think Tapatalk users can be effectively separated/distinguished from browser users. But in any case, it's impossible to start a thread from Tapatalk when a post icon is mandatory as the Tapatalk interface doesn't have the option to choose one. I can pick a prefix, but not an icon. Attempting to create a thread's first post throws up an error stating you must choose an icon.