I have a case where the dynatraceMonitor POST is failing with a 404 and doesn't have any parameter. The POST usually comes with a few parameters like type, session, referer, etc. But in this case it is empty...
It makes me think that there may be something abnormal, something not behaving properly
It is possible that agent is injected into properly. First go to start center and there you should be able to find uem health check.
Second of all, uem may have to be reconfigured to send beacons to different url. Because sending it on root of domain may be restricted by webserver.