Blocks are not inserted into context

I'm working on version 10.3.2 with Claro as the admin theme, and I don't have that problem. Try changing the admin theme to Claro and test again.

Regarding the error 'Uncaught TypeError: $(...).once', I have encountered it as well, and there is a merge request to fix it: https://www.drupal.org/project/context/issues/3374119 🐛 Search is broken when placing block RTBC .