Would it be possible to recreate the issue by launching the login page and at the same time looking at the Initiator column in Chrome Dev tools (under Network tab) to see who is causing the redirects? Can you take a screen shot of Chrom Dev Tools or fiddler and add it here?
So what I think it happening is that the Error Redirect which is being caused by another transaction causes UEM malfunction, meaning it stops capturing data. Somebody on my team was running a synthetic load test and once the errors occurred, I notice UEM stop capturing the manually metrics. So that is the real issue now.