Sometimes issues occur when uploading images in Optimizely CMP.
We’ve identified that some required URLs are not included in the CMP documentation, which causes problems in environments with strict proxy configurations.
We recommend that the CMP engineering team ensure the documentation is kept up to date whenever new URLs are introduced.
Based on our current observations, the following URLs should be added to the documentation:

https://www.filestackapi.com/
https://browser-intake-us3-datadoghq.com/
https://js.userflow.com/es2020/userflow.js