GadgetBridge reconnection does not work if Whitelist enabled

it's strange that it's still possible to reconnect with (presumably) different address as long as I do not leave the settings app.

I think it's because the settings are only properly applied when you exit the app.

I think this is closed then - the 'Read more' section of the Settings app does say pretty clearly:

NOTE: iOS devices and newer Android devices often implement Address Randomisation and change their Bluetooth address every so often. If you device's address changes, you will be unable to connect until you update the whitelist again.