That’s a strange error, and we’re not sure what to make of it.
It’s a bit of a long shot, but you might try following the instructions here on the problematic machine and see if it helps:
Another possibility is that you network and/or Zscaler requires an HTTP proxy, particularly for POST requests. Unreal Engine does not automatically use the proxy configured for Windows. If this is the problem, some users have been able to solve it as described here: