Older MacBook Pro doesn't see new modern Bluetooth speaker, why not?
Thankyou for the level of detail you've provided. Saying that, it's unclear from Sony's spec page as to backwards compatibility.
Your MacBook can do up to bluetooth 4.0, the speaker is 5.0, which according to the standard is backwards compatible with 4.0 &amp; 4.1.
When you say you've debugged bluetooth on MacBook, what steps did you use?
The bluetooth module is combined with wifi, so if you reset it I'm imagining you needed to setup wifi again?
If your investigation doesn't go anywhere, an option would be to buy a small usb bluetooth 5 dongle. You may need to tell the Mac to ignore the built in module. Details here. Force OS X to use Bluetooth dongle instead of built in controller
Hope you are able to resolve it. If not usb adaptors are pretty cheap.
Sorry should've added that specifying an address in bluetooth is not really a thing. device and service discovery are really the only path to connecting any bluetooth device.