RoboHelp 2019 Classic and SharePoint connectivity issue

Suddenly I am getting RoboHelp 2019 connectivity issue with SharePoint. Getting the following error:

As mentioned in other posts, I am working in an organization where I've whitelisted the required URLs (i am able to access them via browser). I can also access the sharepoint with web browser but having issue with RoboHelp.

If you know the reason for this or anything that we can troubleshoot, please share.

Thanks,

Ahmed