Filter by last not blank date in Power BI

I have data from multiple countries on a monthly basis. Since the updates are not regular, I want to set up filter to visuals, so they would show the last month for which I have data from all the countries. I have data from each country loaded into a separate dataset, which then are merged into one big. Is there an easy way to place such filter? I managed to use "LASTDATE" function in each of country sets to find which date is last, but if I try to filter with that measure, I simply get nothing in a result. Thanks!