Summarize According to selected time Interval

Hi andrezmor ,

First of all believe that you are counting 12 additional hours on the Class C according to your data the C values are has accordingly:

If your filter is based on the 3/5 and 3/7 only the third line is consider makingi it the 24 hours and not 36, I assume you are counting also the first 12 hours from the first line but it does not match the filter.

Try the following measure:

Total Hours = 
VAR temp_table =
    FILTER (
        SUMMARIZE (
            ALL ( 'Table'[Event Class], 'Table'[Start Time], 'Table'[End Time] ),
            'Table'[Event Class],
            'Table'[Start Time],
            'Table'[End Time],
            "@HourDifference",
                DATEDIFF (
                    MAX ( 'Table'[Start Time], MIN ( 'Calendar'[Date] ) ),
                    MIN ( 'Table'[End Time], MAX ( 'Calendar'[Date] ) ),
                    HOUR
                )
        ),
        [@HourDifference] > 0
            && 'Table'[Event Class] IN VALUES ( 'Table'[Event Class] )
    )
RETURN
    COALESCE ( SUMX ( temp_table, [@HourDifference] ), 0 )