2nd Login Required for Workflow Query Task

We are using Windows Integration security on our HTML5 2.4.1 viewer and GE 4.3.1 Manager. We have 2 workflows that queries a secure REST endpoint to populate combo boxes in a display form. We have permission set (green check) to allow with Windows Integrated - All Users.

Whether we using an internal network connection or if we're out in the field, we always get a 2nd login box when using the tool. After running Fiddler, we noticed a HTTP/1.1 401 Unauthorized error when we first start either workflow. We're using the same secured REST endpoints in the map and we don't get additonal logins after initial login.

Anyone else seeing this as well?

Thanks!