Rudder

M| State         Technique                 Component                 Key                Message
E| compliant     Common                    ncf Initialization                           Configuration library initialization was correct
E| compliant     Common                    Security parameters                          The internal environment security is acceptable
E| compliant     Common                    Red Button                                   Red Button is not in effect, continuing as normal...
E| n/a           Common                    Process checking                             Rudder agent proccesses check is done by the rudder-agent cron job
E| compliant     Common                    CRON Daemon                                  Cron daemon status was correct
E| error         Inventory                 inventory                                    Could not install Xen utils on Xen system
E| error         Inventory                 inventory                                    Generated inventory has been detected as invalid
E| compliant     Common                    Binaries update                              The agent binaries in /var/rudder/cfengine-community/bin are up to date

All from vanilla 4.1.0.rc1 agent on sles12sp2 being accepted on a same-versioned root server (no relays).

The system is a PV Guest.

# xen-detect
Running in PV context on Xen V4.7.

Here are some relevant lines from running it in verbose mode

 verbose: Unable to detect environment from cf-monitord
 verbose: This appears to be a SUSE system.
 verbose: Looking for SUSE enterprise info in 'SUSE Linux Enterprise Server 12 (x86_64)'
 verbose: Discovered SUSE version SuSE_12
 verbose: This appears to be a xen hv system.
...
rudder  verbose: C: discovered hard class xen
rudder  verbose: C: discovered hard class xen_domu_hv
...

But in the bundle agent fusionAgent you don't handle this case:

    SuSE.xen_dom0::
      "xen_tools_package" string => "xen-tools";
    SuSE.xen_domu_pv::
      "xen_tools_package" string => "xen-tools-domU";
    debian::
      "xen_tools_package" string => "xenstore-utils";
    !debian.!SuSE::
      "xen_tools_package" string => "xen";

Please add xen_domu_hv to that line with "SuSE.xen_domu_pv"