I have created the following DAX measure, and it returns a blank

MyTest = 
(CALCULATE (COUNTROWS(FILTER('Treatments All',
'Treatments All' [Treatment Status] = "Completed")),
DATESBETWEEN('Treatments All'[Treatment Date], TODAY(), TODAY()-90)))

I have tested the exact same measure with other dates and it seems to work, so why is it not working when I use TODAY() and TODAY()-90?