The anime show in question is 22/7 and the listing at TheTVDB is here.
Before, Plex was able to match with it but now it won’t at all. Even using the match dialog bears no fruit. When it did match with it, it wasn’t downloading the artwork for it for some reason. However, other metadata such as episode names, it was downloading just fine.
My guess is that the trouble is caused by the forward slash in the title.
Server Version#: 1.18.8.2527
Player Version#: 4.22.2
Try a manual Match/Fix Match and click Search Options. Use 22/7 as the title, but try The Movie Database as the agent instead of TheTVDB. I just performed a quick test here and that seemed to work.
I did it manually as well and it couldn’t find it. I prefer TheTVDB if possible since it has episode names. I wanted to draw attention to this as it could be a bug.
I also see no match when testing against TheTVDB. But there has been some weirdness with them for the last two or three days which may be contributing to the matching failure (though, to my knowledge, that issue only affected metadata).