SUM all rows whilst using a filter

Here's how I accomplished this:

• Created a Date table and related that to your main table
• Created two project tables, one related to the table and one not

Use the column from the "DiscConnProject" table for your slicer

use the project column from the project table for rows on your table

The following measures collect the min and max of the project selected:

FirstDate of Selected = 
CALCULATE(
    FIRSTDATE( 'Date'[Date] ),
    FILTER( 
        ALL( Table1),    
        SELECTEDVALUE(DiscConnProject[Project] ) = Table1[Project]
    )
)

LastDate of Selected = 
CALCULATE(
    LASTDATE( 'Date'[Date] ),
    FILTER( 
        ALL( Table1),    
        SELECTEDVALUE(DiscConnProject[Project] ) = Table1[Project]
    )
)

then a simple total:

Total Amt = SUM ( Table1[Amount] )

and the last measure:

Measure = 
CALCULATE( 
    [Total Amt],
        FILTER( 
            ALL ('Date'[Date]),
       'Date'[Date] >= [FirstDate of Selected]
       && 'Date'[Date] <= [LastDate of Selected]   
        )
    ,
    ALL( DiscConnProject)
)