I don't know everything about the process but I did just drag out a five-month-old post on my game's forum out of the modqueue a few days ago. It was very well hidden and I had no clue it was there.
I'm not sure if it needed to be approved by only the dev, or if itch.io had previously approved it, or if it was also in their mod queue and could have been approved by itch.io instead of by me.