Putting this here as I struggled for ages trying to get it working. It would not work until I Cleared Cache Data under the Configuration > Performance section. After that for each theme/language change I had to do that again for it to work.

My cache settings are (for the developers, in case they want to test/document/code for this scenario):

  • Caching mode: Normal
  • Minimum cache lifetime: 1 hour
  • Page compression: Disabled
  • Block cache: Enabled
  • Optimize CSS files: Enabled
  • Optimize JavaScript files: Enabled