Measure to replace null date with specific date

pls try this

if ( ISBLANK(yourtable[End_date]),TODAY()-1,yourtable[End_date])
-----------or---------------------
if ( ISBLANK(MAX(yourtable[End_date])),TODAY()-1,MAX(yourtable[End_date]))

Hi Ben1981 

Maybe you can try this:

First of all, I created a sample:

Transform Data > (Right-Click the null) Replace Values.

Insert null(or other values that don't affect the report)

Change the second null into

Date.AddDays(DateTime.LocalNow(),-1)
//Use M Query to return the date/time yesterday.

Like this:

Then change the column type to Date.

The result is as follow:

Documentation on M Query:

Power Query M function reference - PowerQuery M | Microsoft Learn

Time Queries:

DateTime functions - PowerQuery M | Microsoft Learn

Best Regards,

Zhengdong Xu

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