Join-In Progress Seems to Not Work

I check the option, I get put in literally anything but games in progress while there's a bunch of grieving tanks and healers trying to and getting kicked lately.

It's almost as if games in progress aren't even top priority while the option is turned on. Is this intended? If so, then what's the big idea here!? How can you join in progress when it's not top priority? You can't just expect it to work if it opts to throw in a new game over one in progress cause then what is even the point in having the option?

If not then what gives!? Is it a glitch in the system???

If memory serves, your priority is based on time spent in queue, In-Progress or otherwise.

So, a group waiting for a healer for 15 minutes In-Progress will have less priority than a group waiting for a healer for 20 minutes fresh.