Option 1The most common reason why the plugin UI is not working is that other plugins or themes are having conflicts with Duplicator. To turn off other plugin hooks when using Duplicator go to > Settings > General Tab > Advanced then check both boxes for:

1. Foreign JavaScript – OR – “Other Plugins/Themes JS”
2. Foreign CSS – OR – “Other Plugins/Themes CSS”

Then try to reload the page/view you were having issues with.

Option 2If option 1 does not work, consider deactivating your plugins or trying another theme temporarily. Then try to reload the page/view that was having issues.

Option 3If option 1 and 2 still provide no solution then follow these steps to find the JavaScript error that may be occurring.

1. Open your browser console, how-to instructions here: https://balsamiq.com/support/faqs/browserconsole/
2. Retry the action that was causing issues.
3. Copy any error messages that show up in the browser console and create a help ticket. An image screen-shot capture is preferred.

Option 2Possible Cause: A third-party theme is corrupting the Ajax call response
Resolution: Activate the default WordPress theme for example “Twenty Twenty” and then try to reset packages.

Option 3Possible Cause: The server is running out of memory or time to process the reset.
Resolution: Increase value max_execution_time and memory_limit variable in php.ini. If this is beyond your abilities or you don’t have permissions todo this then contact your hosting provider.

Option 1To view the packages menu the current role of the logged in user must have the‘export capability’. This means the user your logged in as should have a role of’Administrator’. Go to > Users > ‘Select User’ > ‘Role’ setting > set to ‘Administrator’, then logout and login. If thisoption still does not work consider these options below.

Option 2

• Try User Role Editor Plugin:Install plugin, then enable the ‘export’ capability on the current role(most commonly Administrator).Note: When editing Administrator you must enable “Show Administrator role at the User Role Editor” in the Settings >User Role Editor menu.
• Edit functions.phpAdd the following to your functions.php
  $admin_role = get_role( 'administrator' );
$admin_role->add_cap( 'export', true );


Also see:
WordPress Form: Menu Tools – Export Missing
WordPress Codex: Roles and Capabilities