Branding created in studio is not available after update

To reproduce :
Mark your target platform in studio as 5.7.1 + DM
Create one or several brandings in studio (in my case: Bla-Bla)
Important: do not check your brandings as default
Save the brandings
Update platform
Go to a workspace, manage tab, local config subtab
Enable theme configuration
Branding does not appear in flavors list