Importing Test steps to existing Zephyr Tests

Hi

We are moving a project between Jira cloud instances.  I have imported all issues including Zephyr Tests.

Now I need to import the Test Steps from the old instance but I've come across what looks like a catch 22.  Apparently it is a pre-requisite of the importer for all imported fields to be on the Create screen  BUT the Zephyr test steps don't appear on the create screen and can't be added to it.

Any ideas how to resolve this.  I can't face keying in nearly 1000 test steps.

Thanks

Edited to add, I'm trying the old Zephyr Importer that I used successfully many times on Jira Server.  Instead of add steps to an existing test, it now creates a new one and then gives "Unable to add testcase ending at rowNumber - 9. Error:Unexpected response code: 401 Your presented credentials do not provide access to this resource."

I've recreated my access and secret keys and I'm certain of my username and my permissions

I'd be grateful for some help.