SWITCH and ISFILTERED combination

Using INSCOPE instead of ISFILTER does the job

Fixed cost var filters = 
SWITCH(
    TRUE(),
    ISINSCOPE(dDate[Year]),
    DIVIDE(
        CALCULATE(
            SUM('Fixed Cost per Month'[fixed Cost]),
            ALL('Fixed Cost per Month'[fixed Cost])
        )
        *MAX(dDate[Month Number]),
        [Dedicated Shipments]
    ),
        ISINSCOPE(dDate[Month]),
      DIVIDE(
         SUM('Fixed Cost per Month'[fixed Cost]),
            [Dedicated Shipments]
        ),
        ISINSCOPE('Prototype Modeling_Freight'[Plant Cluster]),
        DIVIDE(
            SUM('Fixed Cost per Month'[fixed Cost]),
            [Dedicated Shipments]  

                ),
                ISINSCOPE('Equipment Master'[Max Loadability in Tonns]),
                
                DIVIDE(VALUES('Fixed Cost per Month'[fixed Cost]),[Dedicated Shipments]),BLANK()
    )