Currently, you can grind Shanty Town for Dilithium by just re-requesting the mission (your fleet should be running both red/blue sides in a private match).

I found that on the 3rd play through, the mission will be counted completed just before the end of the match. So, when you see that you have 3/3 missions run and the 3rd is just finishing, don't leave the map. Turn in the mission and re-accept it prior to leaving the map. When you come back to the mission (grinding dilithium) it will show you as already having run and won the first mission! Juswt run 2 more real missions in Shanty and you're already done.

Nice one. Moved to confirmed and premium to you.

Wow, thanks!