I have just attempted to move all of my local vault items over to the Teams-based "Your Vault", and almost all items transferred successfully.
Unfortunately three items, failed to transfer, and if any of those three items were included in a batch of items, the whole batch would fail to transfer. No reason was given.
As an experiment, I created a new local vault ("Test Vault"), and the items transfer fine to it. I can not transfer those items from "Test Vault" to "Your Vault" either. Because of this I've posted under the Teams Beta forum, as it seems to work fine between local vaults. I can repost to the main Mac Beta forum if necessary.
There's nothing particularly strange about the three items. One is a login, two are software licenses, and all three contain email attachments (though most of my items do).
Obviously I can't send you the data, but I'd be happy to discuss the contents privately if necessary.
1Password Version: 5.5-BETA15
Extension Version: 4.4.4
OS Version: OSX 10.11.1
Sync Type: Dropbox