STEPS TO REPRODUCE:
1. The customer's servers are in a DMZ environment and no access to the outside world and Clarity is Non SSO.
2. Login to Clarity.
3. Navigate to Modern UX.
4. On Projects -> Project -> Status Report, click on Preview.
Release : 16.0.3,16.1.0,16.1.1
In this case the internalUrl doesn't work since it's not an SSO environment and the export still fails.
We are reviewing this as DE68639.
Fixed in 16.1.2, 184.108.40.206(Patch 1), 220.127.116.11 (Patch 4)