When an outage occurs on an UIMHost model, it is not computed in the availability report.
The reason behind this behavior is because of the Event Processing Filter located in $SPECROOT/tomcat/webapps/spectrum/WEB-INF/repmgr/config/availability-up-down.xml file does not have the up and down events generated by the spectrumgtw probe.
This issue has been addressed in the following patches. Please contact CA Spectrum support:
Spectrum_10.02.01.D265
Spectrum_10.02.02.D285