A user is space admin and owner of an app, but they are not able to export it from a shared space. The option is not present.
Moving the app to the personal space allows the export.
Environment
Resolution
This is is usually caused by the user being defined as "USER" in a section access table.
Change that to "ADMIN", as specified on the help site.
NOTE: Defect QB-14213 is currently preventing exports for as admins as well. A fix is expected at the beginning of October 2022. The workaround is to temporarily move the app to a personal space.