how to summarize one table whose data are from two fact tables

Ok, see if this works. 

Count Items w/forecast =
COUNT ( 'Forecast Fact'[Item] )

Above Forecast =
COUNTROWS (
    SUMMARIZE (
        FILTER (
            'SKU List',
            [Production] >= [Sum Forecast]
                && NOT ( ISBLANK ( [Production] ) )
        ),
        'SKU List'[Item],
        'Vendor Lookup'[Vendor]
    )
)

I've attached the PBIX file