From a colleague on the field:
There is a problem when MTC-NM has an alert published IF the alert's
origin NM region link with the (NM) MTC-NM region publishing the
alert is dropped or is recycled. The alert is left FROZEN on the
(NM) MTC-NM publishing it.
Support note: This happened there with a SEV1 alert--it was reporting
exactly that: The link had come down.
SE raised SO06141 plus instructions on how to set up $GLBL LINKAL OFF
(on NMINIT) were e-mailed out--and tested successfully.