I've got it installed on Edge and Firefox and most of the time it says 'medium.com is not supported' so I've just downloaded it to Chrome, where it works, but not very well. Now it's started working on Edge (although clicking on the suggestions doesn't automatically accept them). It will probably be broken by morning. We'll see.

For my magazine work, I usually leave things a few days so my proofreading is better, but I'm more compelled to publish quickly on Medium. Hopefully, if I can get this working consistently, it'll help. It's working now. Weird.