Can't upload media on main site since the migration

My subdomain multisite was recently migrated to your hosting, but since then, I can’t upload media to the main site. And get this error when we try: Unable to create directory: uploads/2019/07.

Uploading to subsites works fine though.

During a live chat session, we checked everything we could think of, and discovered that the install has a blogs.dir directory where the subsite uploads folders are located. That doesn’t really make sense as this was a relatively new install at GoDaddy before the migration.