An internal global signal's source logic element (LE) and one or more of its destination LEs are in the same logic array block (LAB).
Move the destination LEs to another LAB.
An internal global signal feeds non-global logic in addition to global signals.
Duplicate the global signal source logic making one of the signals global and the other non-global. Use the non-global signal to feed logic.
This problem was fixed in the MAX PLUS II software version 9.1.