Hi,

There might be some features added and enhanced in DX8 that caused the issue.
What you can try on your end are : 

Check for Deprecated Functions

Identify any JavaScript functions used in your Joget v6 application that may be deprecated or replaced in Joget DX8. Joget DX8 might have introduced new methods or changed the way certain functions work.

Update JavaScript Libraries

Ensure that any external JavaScript libraries you are using are compatible with Joget DX8. Update these libraries to their latest versions if necessary.

Modify JavaScript Code

Adjust your JavaScript code to align with the new APIs and features in Joget DX8. Here are some common changes you might need to make:

• AJAX Calls: Ensure your AJAX calls are using the correct endpoints and parameters for Joget DX8.
• Form and UI Customizations: Check if the HTML structure or CSS classes have changed in Joget DX8 and update your JavaScript code accordingly.
• Event Handlers: Verify that event handlers (e.g., onload, onclick) are still correctly referenced and functioning.

You can also have a read on this KB : Updating to DX 8 AJAX Themes.
it has the potential fixes if your JS scripts are not working as expected after upgrading from older joget version to Joget DX8.

Cheers!