This issue occurs when the asset discovery takes too long to load the webpage assets (due to the asset being behind authentication/firewall, or a different domain than the current webpage, etc.). To debug this issue, please enable the debug logs before executing a Percy build again, and inspect for the failed HTTP/S requests messages in the logs:
For Linux/Unix (run the below command on your terminal)
- export LOG_LEVEL=debug
- export PERCY_DEBUG=*
For Windows (run the below command on your Command Line/PowerShell)
- set LOG_LEVEL=debug
- set PERCY_DEBUG=*