Bose Soundlink bluetooth speaker keeps disconnecting from MacBook Pro

I used to be able to use my Bose Soundlink Micro speaker with my MacBook Pro (2017, 13'', running the latest Catalina update) with no problems, but since a few months, I cannot.

The pairing seems to be working fine (as is confirmed by the System Report's info on bluetooth), but whenever I try to connect the speaker, it disconnects immediately (the voice prompt cannot even say it's connected before it starts saying it's disconnected).

The problem is specific to this connection: my MacBook Pro accepts other speakers, and my Soundlink can connect to other devices.

I have done ALL SORTS of troubleshooting (bluetooth resets on both sides, PRAM and SMC), and have asked on the Bose online support to no avail, so I am trying my luck here.

(For reference, here is the Bose support thread https://community.bose.com/t5/Portable/Bose-Soundlink-Micro-connects-disconnects-immediately-to-from/td-p/530147)

The latest from Bose was to suggest that the bluetooth profile of the speaker was not compatible with that of the MacBook Pro (they said the speaker needed A2DP, AVRCP, HFP, or HSP. As far as I am aware, at least the last two are supported by my MacBook Pro.)

Hopefully someone has a brilliant idea... thanks!

Benjamin