DAX - Using measures to filter chart on specific years

I have the following issue that I don't understand how to solve it. The following scenario exists:

I have a data table that contains subscription data with a date column and a column "balance" that contains either a +1 for a new subscription or -1 for a subscription end. That means, to get the amount of subscriptions on a specific date, I need to do a running total.

To do this, I have added a date slicer with the following values:

From: 01/01/2004

To: 06/29/2021

To get the running total, it works perfectly fine with the following DAX calculation:

balance RT = 
VAR RowDate = LASTDATE(Dataset[measureDate])
RETURN
CALCULATE(
    SUM('Dataset'[saldo]),
    FILTER(
        ALLSELECTED('Dataset'),
        ISONORAFTER('Dataset'[measureDate], MAX('Dataset'[measureDate]), DESC)
		 && YEAR ( 'Dataset'[measureDate] ) = YEAR ( RowDate )
    )
)

Next thing I want to do is to put this on a graph and only show data for 2020 and 2021. To do this hardcoded, I changed the above DAX formula to the following:

balance RT = 
VAR RowDate = LASTDATE(Dataset[measureDate])
VAR measureDateFrom = DATE(2020,1,1)
RETURN
CALCULATE(
    SUM('Dataset'[saldo]),
    FILTER(
        ALLSELECTED('Dataset'),
        ISONORAFTER('Dataset'[measureDate], MAX('Dataset'[measureDate]), DESC)
		 && YEAR ( 'Dataset'[measureDate] ) = YEAR ( RowDate )
         && 'Dataset'[measureDate].[Date] > measureDateFrom
    )
)

This also works perfectly fine. But obviously I don't want to have that 2020 hardcoded in that third line and therefore I have created a separate measure:

DATE(YEAR(LASTNONBLANK(Dataset[measureDate], Dataset[measureDate]))-1, 1, 1)

This works fine when I display this specific measure in a card visualization. Now, when I integrate this into the above DAX formula, it doesn't work. It seems like the date is not calculated properly because all the data is still displayed in the chart. It looks like this "2020" that is the outcome of this separate measure, is not properly evaluated in the above formula.

Would anybody be able to help out here? Thank you in advance!