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there seems to be a bug in the Windows wallet. If the wallet is unlocked for staking only it does not allow the creation of new transactions. To create a new transaction the wallet must be locked and then completely unlocked again - then it is possible
I don't consider that a bug. It is a safety feature that stops your coins from being stolen while you are asleep staking. I feel very safe knowing that no-one, not even myself, can send my coins without entering the passcode while the wallet is unlocked for staking only.
I would agree if it would be required to enter the passphrase again to create a transaction. But it is necessary first to lock and then to unlock the whole wallet. That cannot be intentional. Its clearly a bug (even a minor one)