On my site in MT, the highlighter feature is not working.
Also, after I change a css setting in MT, the processing wheel in the upper left corner spins and never stops, and the changes never show. I have to refresh the screen or look at the actual site on another browser to see the changes.
This definitely sounds like a JavaScript issue is preventing Microthemer from working properly. If you can send me login details for your site via this secure contact form I will investigate a fix for you: https://themeover.com/support/contact/