Dear Kamal,
Can you please deactivate the plugin one by one and check if the issue solve. Technically the issue is cause by ajax failed request or some bad response from Customizer API, which usually cause by badly written plugin.
If the issue persists please contact us here https://www.acmethemes.com/contact/ , We will look on your site to check what is causing the issue.
Note : Our live support is available on 10am to 6pm on Working days, Time Zone GMT+5:45
Best Regards!
Acme Themes