Hey @CTRIM - we've been having the same issues of the Alert "Detected Unrecognized Requests" being displayed on Horizon's Dashboard similar to the following since we upgraded from Horizon 7.x to 8:

When we drill into the details for the affected CS a bit more we don't get much better info except that there are "XML API Unrecognized Requests":

We don't use UAGs but instead some F5 appliances in our case.  Also the server may vary as well as the number of unrecognized requests - oh and in fact sometimes no CS are actually listed ... just that there are issues . 

We tried to poke VMware support for more details on this and they came to a similar conclusion that they were just "noise" and could be ignored.

Unfortunately I'm not super thrilled about that response since as I think was mentioned, it kind of makes a mess on the Dashboard's System Health section and could lead to accidentally ignoring real alerts.  I wish there was a was to totally suppress these alerts if they are indeed totally ignorable ... aheem VMware gods if you are listening ...

In any case - anyone come across a fix of sorts that they know works please post it here.