There could be an increasing delay for the time a project gets listed, if you submit "too many". So you could upload the project, but additional projects would only show up delayed in search and browse.
Or, since the browse is somewhat weighted, the weight could get calculated different, if a creator has many projects.
But for most recent, just wait 24 hours. Then they are no longer on page one. Sometimes people migrate their stuff here, so a lot gets uploaded in a short time frame.
And if you catch someone reuploading the same asset over and over, report the account for low effort posting. I believe somewhere in the faq or tos it says, that they will delist your stuff, if you do such spamming.