For about a month, myself and others in my organisation have been unable to convert a newly-created portal from "trial" to "production". This was previously possible via taking ownership of the application in Azure AD, but recently it failed every time, with the error message "You cannot convert your trial portal to production as you don't have an appropriate license". Our organisation uses the now-retired Customer Engagement Plan licenses and it wasn't at all clear what was meant by we didn't have an "appropriate license". I lodged a support case with Microsoft Support.
After approximately two weeks - indicating that it wasn't a commonly-known fix - I received advice that the remedy was to purchase and apply either: Power Apps portals page view capacity add-on (minimum 50,000 licenses per portal); or Power Apps per app plan (minimum 100 per portal). Following this advice did remedy the issue and I was able to convert the three portals in question from trial to production.
I queried whether we would be able to "return" the licenses or have them refunded, as now the issue was fixed we had no further need of them. The support engineer advised that this was not a technical bug, but rather had been implemented by design and the implication was that there would be an ongoing need for the add-ons.
I am posting this publicly not only to ensure that others searching for a solution to the issue may find this, but also to call out Microsoft on this approach to the issue. As a business practice I view it as unethical and designed solely to sell additional add-on licenses where they are not needed for any other purpose. I am very disappointed in Microsoft for effectively requiring customers in this position to purchase additional products to remedy an issue solely created by them.