That sounds like an issue Qualtrics may need to investigate. I’ve seen lags of a few minutes for updates to appear before, but nothing as long as you described. I would suggest contacting their Support.

@buckeye_jay Did the preview updated? You can check the version history to see your change and try to access it through anonymous link in incognito mode. If it’s still not. You should contact the support.
 

@buckeye_jay sounds like your doing the main things, like clearing cache.  The only other thing to check is, are you by any chance checking it using an existing link you have already clicked/started to complete.  The changes will only apply to surveys where existing session hasn’t started.  You should be able to see changes under survey preview regardless but if testing through live link any changes only apply to new sessions.  If this isn’t the issue then definitely raise a support ticket.

When clearing your browser/cache, you could make sure you’re clearing it for the right time frame too. Instead of only clearing cookies for the past 24 hours, you may have to do a week for example.

I see I’m quite late. I’ll answer for future reference.

After activating your survey, you have to go to Data & Analysis. Here you can find the responses in progress. You have to delete the sessions here because they already started the survey with the old version. Or you can finish the survey session and try again.