Unable to see all sites in the go to menu in UMP after upgrade to 8.51

Document ID : KB000100351
Last Modified Date : 06/06/2018
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UIM/UMP upgrade completed successfully and some configured sites are missing from the UMP Go To menu.  Only seeing 10 items in the Go To list and there are more than 10 sites configured.
Why are some sites missing from the UMP "Go To" menu after completing upgrade to 8.51?
UIM/UMP 8.51
During the upgrade the portal-ext.properties file is overwritten and any customized changes will be lost.  Prior to upgrading UMP to 8.51 the UMP was customized to display more than 10 sites in the Go To menu (the default max entries in this list).  Restoring the portal-ext.properies configuration changes prior to the upgrade resolved this issue.
Additional Information:
See the following for how this is set up:

KB000100245 :How to increase the site limit listing in UMP