Change in FIX AND behavior with 25.08

In my business rules, I often use SET EMPTYMEMBERSETS ON; along with FIX statements to handle different branches of logic that need to occur for different years or scenarios.

After our 25.08 upgrade, my users reported data points being written that previously had not been. My logic was as follows:

FIX ("OEP_Forecast", "OEP_Working", "0000") 

    FIXPARALLEL (4, @RELATIVE("Total LOB", 0)) 

        FIX ({Years} AND &OEP_FCSTStartYr) 

            FIX (&OEP_FcstMnth : "Dec") 

                FIX ("101") 
                    /* logic */
                ENDFIX
             ENDIFX
         ENDFIX
        /* FUTURE YEARS*/

        FIX ({Years} AND (@RSIBLINGS(&OEP_FCSTStartYr))) 

            FIX ("Jan":"Dec") 
                FIX ("101") 
                    /* Logic */
                ENDFIX
            ENDFIX
         ENDFIX
    ENDFIXPARALLEL
ENDFIX

Where {Years} is an RTP configured to accept multiple years. Users would input a list of years, say FY25, FY26, FY27, and the logic would only calc the forecast months for the current year and then all months for the out years.