Glenn I'm not sure what you've tried, but have you tried the trivial option of deactivating on the previous computer then reactivating on the new computer? This can all be done in NI License Manager.
In the past when I've distributed applications with my licenses and the customer won't / can't deactivate for me, I've emailed NI and they've deactivated for me. I've never had issues activating on new computers, even with single use licenses and transferring but this new NI business model could have changed things. Does it say activation failed when you try?
Side note, I don't think any of us are happy about the new subscription model and we've voiced that to NI. However us Alliance Partners can only be on subscription so we're used to it but it's a lot more affordable since we're integrators.