Actually I just did a search myself and I found lots of full servers. Unmark all your maps under the filters and be sure to have only "Official" and "Ranked" servers marked under "Type". Anything else you have marked, unmark it and again under the "Free Slots" menu, just mark the 3 above and unmark anything else.
If you have marked some other stuff under different menus such as "Mode" or stuff under "Advanced Settings", unmark it. After this try again and if it does not work, then maybe your region does not have many servers active sadly. I am searching under EU region, so that could be the case. If you dont mind a little bigger ping, try another region.
