We haven't gotten to the root of the issue yet.
Trying to reproduce it on a website using the core template will tell us whether your template is causing the issue.
Probably yes. But I understand if you do not want to go into the trouble of figuring out the cause.
Anyway, if you want to buy a different extension with the amount you paid for Better Preview, I will have to refund your Better Preview purchase.
If you want that, let me know.