I worked it out myself.

For anyone having the same issues, deactivating all plugins will allow the import process to work.  Reactivate your plugins afterwards.

It’s probably one plugin causing the issue but I just deactivated them all to save time trying to find the culprit.  In fairness, Codeless recommends that you complete the process on a fresh install where as I had already added a ‘coming soon page’ plugin to hide the development process so it was probably the offender.

Give it a go, it should work.