Friends stranded in Mt. Gulg for 10 minutes, In Progress healer didn't help

[Catwho]

My friends lost their healer due to a disconnect. They had been waiting for a new one for ten minutes. I swapped to heal, set my party finder to In Progress, and queued for Mt. Gulg.

After a full minute of waiting, it tried to put me in a fresh instance of Mt. Gulg instead.

So I withdrew (apologies to those who I guess got it in roulette), waited another couple of minutes after that..... and tried it again.

And got another fresh instance, after about a minute. I assume if it was someone queued specifically for Mt. Gulg that needed only a healer, it'd have been instant, but there was a full minute of being queued for Mt. Gulg and nothing else, and there being 0/1 tank, 0/2 DPS, before filling all at once.

Another person in our linkshell tried again.... and the same thing, but he rolled with the dungeon rather than abandon, since he needed exp anyway.

They eventually abandoned their in progress dungeon after waiting for 15 minutes, with no replacement healer able to reach them. They assumed they had glitched out.

Does the Duty Finder matcher not prioritize Party in progress that is recruiting to try to replace lost team members?

(We are on NA. All four of my languages are checked because I've done rescue/replacements before and I know that's one of the things DF may check. So I shouldn't have been locked out for language. Party in progress was definitely on.)