Issue with calculating median using filters

So I have a date table like this:

Formula for "Median Time Taken Performance (Over Time)", which is supposed to show the median time taken for all items with the specific date is

Median Time Taken Performance (Over Time) = CALCULATE(MEDIANX('FACT','FACT'[Time Taken]*1.0),FILTER('FACT','FACT'[Column]='Date Table'[Date]),FILTER('FACT','FACT'[Time Taken]>=0)).

However, for some reason it is not showing a median for some of the dates, even though there is 'Time Taken' data available for those dates in the FACT table:

 If anyone could tell me where I'm going wrong, that would be much appreciated,