Hey @enquiries66, sorry for the trouble! It should work for existing posts as well. Could you try viewing them from an Incognito window? It's possible there's something in your cache/cookies that might be interfering.
In this case it might be best to reach out to our team at email@example.com (or via the in-app messenger in your account) with a description of this issue, the name of the form (as it is displayed on the forms page51 in your account), and the URL on which it is embedded. With that info, one of our Product Specialists will be able to help troubleshoot more specifically :)