Is it possible to be matched up with a member of your ignore list?
Solution 1:
Unfortunately, yes.
Ignore only prevents them from showing up in chat, you can't "Ignore" them from the matchmaking pool.
Solution 2:
Yes, you can . It is a problem though because if you are on draft mode selection , you will not be able to see what they write on chat ( very important for ranked games).
It is said to be less possible to match with ignored users, but I am not sure if this is true .