Update: After adding "TogetherJSConfig_cloneClicks = true" now switching tabs and some versions of selectInput work! However, check boxes, selectizeInputs, etc. do not and neither do changes to a shinyAce text editor.
tags$script('TogetherJSConfig_hubBase = "https://togetherjs-hub.glitch.me/"; TogetherJSConfig_cloneClicks = true;'),
tags$script(src = "https://togetherjs.com/togetherjs-min.js"),