See this match for this mentor who has been marked as not available for some time. This is especially problematic because it takes additional time to find a replacement mentor. After a little investigating, I suspect this might have something to do with the apparent move of Category:Co-op mentor not taking new requests to Category:Co-op mentors not taking new requests. Does this need to be moved back?
It doesn't need to be moved back, but I did need to change that in the config. The change is made and it shouldn't do this again.
In general, if a category the bot relies on to match or not match is changed, it will need to be changed in the config file on Tool Labs.