We have not tested if the plugin works in brave, but if it does and this would be correct. Considering that Brave is essentially just chrome with a few additions I would assume that it likely works.
So first, go into the “Raw Data” tab in activitywatch.
If the “aw-watcher-web” bucket seem to contain data the extension probably works properly in brave.
If this is the case, the data is there but the query from the web-ui to aw-server needs to know the name of the Brave window to apply its filter properly.
If you want to help us to fix that, check your “aw-watcher-window” bucket. Find a event in there which refers to brave and paste the exact string of the “app” field. If we know that string we can add that to the window filter in aw-webui and it should then work in the next release.