It's working on my old macbook, but not working on the new one. Both mac are running firefox esr v52.2.1 on sierra v10.12.6. The only difference I can find is the "last updated date" of the default theme. the working version is July 20, 2017, the not working one is June 28, 2017. I don't know how to update it. It shows "No updates found" when checking for updates. Any ideas to solve this? thanks.