The silly thing is there currently is no way to delete uploaded libraries, otherwise I would try to upload your library to pinpoint the issue.
But that’s no option otherwise the library name would be taken and you couldn’t upload it anymore.
If I take your sources and upload with another name it works for me - no clue why.
Maybe @rickkas7 could have a look and maybe loop in some engineer assigned to the Library Manager.
@richlyon, if you already have an uploaded library, you need to change the version number in the properties file for the update to replace the existing one.
So it's not broken but there must be some other issue - and @peekay123's suggestion would be one possible cause, although I casually dismissed that thought as there was no sign of a previous upload with which yours could have collided, not thinking that there might be a previous private (and since invisible) upload with a higher version number than yours and the system might just check version before ownership.
Since if you try to upload a library which was already uploaded by someone else you'd get a "You are not the owner" message (normally, but with a version conflict the check could bail out before actually realising the discrepancy in ownership).