I am amending my original post. I am using the following DAX code to count the number of tickets closed in the last 7 days.
Tickets Closed Last 7 Days = CALCULATE(COUNTROWS('Service Desk Tickets Closed'), FILTER('Service Desk Tickets Closed', 'Service Desk Tickets Closed'[Closed Date Time] >= [End Date Minus 7])).
Closed Date Time is in date/time format and is in the table. End Date Minus 7 is in Date/Time format and is a Measure. Where this is failing is Closed Date Time is always greater than End Date Minus 7 so it counts every row. There are several months of dates in the table going back to January. The End Date Minus 7 is the 7th of May 2019. I verified that. Am I not able to compare dates this way?