Unable to "Upgrade Vault" on Mac

To migrate your vault, it must be fully synced to your computer. In your case this is not given.

As other cloud storage providers, Apples iCloud offers a feature to save space on the local harddrive by keep the files only in the cloud and download them on demand. To achieve it, a dummy file with the ending .icloud is saved at the location of the real file.

To fully download your vault, read this post: