Step 1: LEAVE the lobby
Step 2: Search ANY DIFFERENT Game-Mode
Step 3: Get in a lobby ( you're likely to get thrown into an already started match quite often tho )
Step 4: LEAVE the lobby
Step 5: Search the Game-Mode you wanted to play in the first place

Thanks to TinyChris, from whom I got this neat little trick.

Have fun, a beautiful day, week, month, year and life.