It happened to me as well!! OMG! so its not my delusion!
this is just a guess but mangago seems to also have an automated bot that crawls on other manga sites and automatically copies any new series.
chapters with blank uploads are automated while the ones with usernames beside them are uploaded by an actual mangago user. that's why there are duplicate series on here, and sometimes an official uploader requests a duplicate to be deleted to have their upload as the sole source.
so, bad luck if the one on my reading list happens to be a bot auto upload that got deleted :(
like i'm pretty sure i added the manga a couple of months ago, but then i see it on the recently updated list- and when i click on it, it shows it's no longer in my list. this has been happening for a lot mangas. i wouldn't even know they got removed unless i saw them on recently updated..
like, is this a case of mangas being reuploaded? does this happen for anyone else?