@Just-Lisa-Now- For the blank sign in screen, it is exactly the problem I'm referring to. Its what we call a new CefSharp component that gets delivered via our Connected Services update. The browser in question is an embedded one and was no longer supported. So when you used the old CefSharp embedded browser (a browser we actually provide, not one you as a customer provides), it won't work because it doesn't comply with new security protocols we need. 

If you haven't tried yet, a "Repair update" may straighten it out to get all the components synced properly.

Best