I'm using the Bootstrap base theme and a sub-theme (cdn) in one of my websites.
Normally everything was fine. Then I installed a fresh Drupal into another server and installed the themes I was using before. The problem appears there, I couldn't change any theme settings of Bootstrap themes via Drupal interface. For example I tick the Fluid container and save but it doesn't change, the box goes back to being unchecked.
The new server configurations may be different from old one.