The reason why the Quform plugin’s “enhanced select” feature only works correctly when viewed with HTTP instead of HTTPS could be due to a security feature in modern web browsers called “Mixed Content Blocking”.
Mixed Content occurs when a webpage served over HTTPS contains resources (such as scripts, images, or stylesheets) that are loaded over an unencrypted HTTP connection. Modern web browsers block these resources by default to protect users from security vulnerabilities, which can lead to the feature not working correctly.
It’s possible that the Quform plugin’s “enhanced select” feature uses some resources (such as images, stylesheets, or scripts) that are loaded over an unencrypted HTTP connection. When the webpage is served over HTTPS, the browser may be blocking these resources, which is causing the issue.
To resolve this issue, you should make sure that all resources used by the Quform plugin’s “enhanced select” feature are loaded over an encrypted HTTPS connection. You can check the browser console for errors and warnings related to mixed content to help identify the resources causing the issue. Once you’ve identified the resources causing the issue, update their URLs to use HTTPS instead of HTTP. This should ensure that the feature works correctly even when viewed with HTTPS.