The source was the same as for the first transfer which wasn't captured. I also made a third large transfer which wasn't captured. However the captured transfer was the largest so you might be right that it exceeded a limit. All transfers were outgoing SEPA. I've only loaded the account with Bitcoin.
Was this (captured) SEPA transfers to your own bank account or to a third party one?
I am also loading with bitcoins and doing SEPA transfers to (mostly) my own bank accounts.