[Zhao Yitian]

Once you connect the Bluetooth MIDI in Audio MIDI setup, it should keep connecting whatever you open the Logic Pro or not (unless you are in battery saving mode, the Xkey will switch to sleep mode every few minutes if you do not play it). The behaiour you linked said everytime you wakeup the computer, you should connect Bluetooth MIDI manually again, that is normal. I thought it was different than your situation.