Project could not be loaded, it may be damaged or contain outdated elements

This seems to be a common issue with multiple solutions none seem to work for me but here what happens and what I have tried:

I have an iMac and a Macbook Pro, both running High Sierra and Premiere Pro 12.0.0 (Build 224).

I have a premiere project which I've been working on using my iMac with no issue.

I now try and open the same project on my Macbook Pro and I get this message : "Project could not be loaded, it may be damaged or contain outdated elements"

I've then tried about 10 different projects all saved in the latest version of Premiere on my iMac and they all do the same thing.

Also worth nothing I used this Macbook Pro with the same projects about a month ago and they worked fine.

So what I tried:

1. Logging in and out of Creative Cloud as detailed here - didn't work
2. Tried starting Premiere holding down the option key to reset the preference - didn't work
3. Tried starting Premiere holding down the shift-option key to reset the prefs and media cache - didn't work
4. Created a new account on my Mac, logged into that and openned the project in premiere - worked fine - so underlying installation is ok
5. Uninstalled Premiere and included option to delete preferences - then re-installed - didn't work
6. Uninstalled Premiere and included option to delete preferences, then manually removed the main prem preference plist file and removed my profile from ~/documents/adobe/Premiere Pro/12.0 - then restartred my mac and then re-installed - didn't work

I don't want to reinstall High Sierra (too much time) and from (4) it would seem the OS is all good with a clean account.

I also don't want to import my projects into new projects - I have too many projects I need to use and some are huge so I don't want to deal with the issues and time of importing them all.

There must be some fix out there but I can't think what else to try.

And frustratingly I leave today for a month filming and editing overseas where internet is pretty bad so re-installing over the internet is going to become an issue.

Anyone got any ideas?

The continued joy of being a Premiere user!!