Apple seems to have intentionally broken this bluetooth in a software update. I also have a W200 that I use as a TV speaker, connected bluetooth to my Apple TV.
In order to get this to work, I bought a preowned Apple TV 4k off of eBay. Thankfully, it came on tvOS 12.3. I then setup a PiHole DNS just for this AppleTV, which blocks all requests to the domains used for Apple Software Update checks. And I don't ever update it. If I would update the tvOS on this Apple TV, I would lose ability to use my bluetooth speaker forever.
Its sad that it has to be this way. It would be nice to be able to update to a newer tvOS version. But it is not worth the loss of the sound through my speaker.