Unable to transfer app to another account

Among requirements to transfer app there is one called "clear all builds and testers and empty all fields under Test Information" under TestFlight but it seems there has been an update to appstore internal code as now I simply can't clear any field under Test Information as error pop ups "There are one or more errors on page." requiring me to fill them. How do I transfer apps now?

Unable to transfer app to another account
 
 
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