Nintex Delegate link is not working inside Nintex Form and redirect to wrong URL

I have Nintex workflow with Nintex forms. In my workflow , i only have an assign flexi task.

Task forms have you can delegate this task to another person with hyperlink.

If i click on delegate hyper link, which is redirect to delagate task URL but the page is broken.

Issue:

I just check on the delegate url, which contain prefix url adding with my two domain name

Example:

Delegate link URL:
http://testingsite.abc.com.abc.com/_layouts/15/NintexWorkflow/DelegateTask.aspx?ID=7677&List=40e7158e-990c-4f71-ad6e-255

but web URL is:

http://testingsite.abc.com

But if i use delegate link in the email content, i dont have issue, but when i using inside Nintex form, i am getting URL prefix issue.

So it should display delegate link http://testingsite.abc.com/_layouts/15/NintexWorkflow/DelegateTask.aspx?ID=7677&List=40e7158e-990c-4f71-ad6e-255

instead of

http://testingsite.abc.com.abc.com/_layouts/15/NintexWorkflow/DelegateTask.aspx?ID=7677&List=40e7158e-990c-4f71-ad6e-255

where can i change delegate setting in the sharepoint central admin or Site collection level.

Please assist me.

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