Quote Originally Posted by Catwho View Post
Languages may also impact this. If at least one person in the party has a language checked that the person trying to fill the in-progress spot does not, then the game will ignore the in-progress. (For example, one player has English and French checked, one has all languages checked, and one has only French checked. An English only queue-er is not going to get into that party.)

The solution is if you are frequently an in-progress rescuer on a role like tank or healer, then make sure all languages in your Duty Finder settings are checked prior to queuing.
I have French unchecked(because be wary of Moogle), yet I've been in several groups where the other 3 people only had French checked, so I don't think this is working as intended.

I hope SE fix this soon. Been an issue since I started this game in 2014.