I've never had this problem until a few days ago. Basically, I uploaded some worlds to my server, and when I tried to go to 'em, the server told me that the world does not exist.
I've tried out file.io, dropbox, as well as directly uploading my worlds (they're all less than 5mb) through the panel, but none of them seemed to work. I've even made sure that my files are not capitalized, and deleted the DIM files, but even that wasn't enough to resolve this issue. From what I've seen, only one world gets to exist, while the others are cucked. I'm suspecting that this is because of EssentialsX since it all started upon installing this plugin, but I could be wrong. I've had some moderators check the server too, but we weren't able to pinpoint the problem.
I'm wondering if there are any other options. Any help is appreciated, I just want to have multiple worlds on my server to hop back and forth between.