Hmm. That 'couldn't find required item at project path' error (if I'm reading your description right) is actually referring to a path inside the project structure (ProjectItems is the virtual "root" folder inside the project itself whose contents are shown in the Project panel). It sounds like your project has actually been damaged or left in a bad state. If you could zip up a project in this state and send it to me, I'd like to take a look and try to diagnose what has gone wrong.
We fixed a bug like that in 1.1 which would occur when performing a Save As operation on a project where the project's name (in the filesystem) matched the name of a top level item in the project panel inside Character Animator.
Anyway, the history in the project might give me enough info to figure out what has gone wrong if you'd be willing to share it.
Thanks -- Dan Tull
That sounds really useful but where do I send the file to? I was going to zip it up and e-mail it or WeTransfer it so I would need an e-mail address (I am new to these forums so only just learning the ropes).
Also FYI the character used in the project is not in the 'Gathered Media' folder but an external folder. I will include it with the project file.