The project in question previously had Skein enabled.
Skein was then disabled and Perforce used for some time.
Now when trying to enable Skein, the following error occurs ;
LogSourceControl: Warning: RunCommandInternalRaw(project create): Errors = ‘BadRequest - Another project with this ID already exists’
SourceControl: Error: Connection Error: The Skein project could not be created.
SourceControl: Error: BadRequest - Another project with this ID already exists