Issues going from free version to premium version

Hi there, I tested your free version and decided to get the premium version. I was able to import the template from the free version using your export and import functions. I could see the import in the preview, but when I hit save, it completely clears the template. And now I can’t make any changes or save them on that template. I can create a new template from scratch and it works fine. Is there maybe a conflict when you’ve had the free version installed previously?

In addition, it also seems that I can’t save changes when creating and editing header and footer blocks. Not sure what is going on there.

Thanks in advance for your help.