Defining two XPC services in a single System Extension

However, when I combine the code and then the plists to define both
XPC services, I fail to create the XPC listener for the Endpoint
Security mach service.

Is this on 10.15.x? Or 11 beta?

This was on 10.15.4.

Code Block  
% sudo launchctl procinfo ***

OK. My next step here would be to check whether launchd knows that the sysex is allowed to publish that service. You can do that with launchctl:

Code Block 
$(TEAMID).$(BUNDLEID) = {
        active count = 3
        copy count = 0
        one shot = 0
        path = (submitted by smd.290)
        state = running
        program = /Library/SystemExtensions/063E252D-C01E-4EBE-96F5-1C5FA0650106/$(BUNDLEID).systemextension/Contents/MacOS/$(BUNDLEID)
        arguments = {
                $(BUNDLEID)
        }
        default environment = {
                PATH => /usr/bin:/bin:/usr/sbin:/sbin
        }
        environment = {
                XPC_SERVICE_NAME => $(TEAMID).$(BUNDLEID)
        }
        endpoints = { 
                "group.$(APP_BUNDLEID).content-filter-service" = { 
                        port = 0xb0ba7
                        active = 1 
                        managed = 1 
                        reset = 0 
                        hide = 0 
                }   
        }
...
}

The service I had defined for the plist key
NSEndpointSecurityMachServiceName is not available.

If ES extension is combined with a Network Extension, set the
NEMachServiceName key in the Info.plist.