[robertfarmer]

Many thanks, that looks like a helpful link. I see what you mean about it being convoluted though.
I've taken your advice and have opened a support case - I'll see what they say before I try anything else. I'll post the response from Avid Support once I get it.
Yes, PT First sounds like it was a crazy product. I've never known anything like it. It's not great to know that all my projects are likely to be trapped in a piece of discontinued software that I can't upgrade. Even if they just offered AAF export in the last version of PT Free would have been helpful.