DAX: how to ignore slicer for particular measure

Data model & dashboard:

Intention: to prevent table visual from resizing due to slicing

Desired outcome:

P.S. Tons of videos watched, but still can't resolve...

Of course in real life model is a bit more complicated.

Currently have to use dirty workaround which includes copy of Id column related with original one with unnatural 1:N relationship (to prevent filtering) and measure with selectedvalue for Num column

Solution

You're sort of skirting the generally intended behavior of slicers, so this isn't quite as simple as you might think it ought to be.

To do this, create a new disconnected parameter table for the IDs:

dimID = VALUES(Table1[Id])

Use this new table for your slicer and write a measure that reads these values.

SumNum =
CALCULATE (
    SUM ( Table1[Num] ),
    KEEPFILTERS ( Table1[Id] IN VALUES ( dimID[Id] ) )
)

Put this in your table and it should behave as expected provided you set 'Show items with no data' on the Table1[Id] column.

Result: