You may be working with personalization conditions on components in the Sitecore Experience Editor, and when trying to preview any of your condition rules – simply nothing changes.
What is going on?
In this case, check if you may have disabled or opted-out the crucial analytics cookie «SC_ANALYTICS_GLOBAL_COOKIE».
This may happen when you integrated a cookie wall, e.g. in accordance with GDPR, and explicitly need to opt-in to any marketing, analytics and/or personalization cookies. In addition, your integration might not EXCLUDE these mechanisms for Sitecore content managers working in the Experience Editor edit or preview mode – basically causing the Sitecore personalization features to feel "broken".
How to set the SC_ANALYTICS_GLOBAL_COOKIE to "true" (workaround)
A) While authenticated in Sitecore and in the Experience Editor
- navigate to your site's cookie wall
- enable the required cookie(s) settings
B) Via the browser developer console (usually accessible via F12 key)
- check if the SC_ANALYTICS_GLOBAL_COOKIE parameter is set to "false" (see screenshot above)
- manually change it to "true". Firefox allows easy modification of cookies in the cookie tab, whereas in Chrome you might need to use a Chrome extension to do so.