Content Explorer ResultCount not set

A mysterious bug has come to light in one of our Rhythmyx installations in that the result count (i.e. number of items) displayed in the top right of the content explorer is output as the literal text string “ResultCount” instead of the actual number of items on the page.

It appers a variable is not being set but I have not got the first clue as to how or where this issue might have occured.

Any pointers greatly appreciated!