Another problem with XE 2016

I am having problems with this line of code:

NEXTBL=SUM(MAXLOC(UNITY,MASK=(NSTRM(PORT,:)==SDMXOUT)))

Unity is an array, all containing the vlaue '1'; I am searching for the location within NSTRM for the value SDMXOUT.

For the current value of PORT, the Mask is False for all entries.  In versions up to XE 2015, under these circumstances, MAXLOC would return 0; under the compiler settings for XE 2016, it is returning 1 (I assume this means that the default for old_maxminloc has changed under this version.  (Incidentally, the documentation does not specify which option [no]old_maxminloc or old_maxminloc returns 0 or 1)

David