Hi there!

Sorry for your issue. I have some suggestions for you! Reason can be one of them:

You may try to go in Advanced > SCSS > Compile SCSS to CSS and turn it on or toggle then save. Once you're done with your colors you can remove it.

You may try enabling compress the CSS and Javascript to get it to work.

Sometimes the main reason for not showing the changes is Adblock software installed on the computer. After disabling the Adblock software the changes are shown immediately.

Clear Joomla and Browser cache(Most important)

Hope this helps!

Best Regards