Thanks for fast reply.
Other options also don't seem to work. This is my first add-on to Aseprite and I haven't used it much before that, so if there is a thing I need to enable for brush properties to take effect it's probably I haven't done that (all I have done it add the plugin and enable it in the settings)
Not sure what Aseprite is built on, could also be an Apple Silicon thing?
If you need me to try anything out for you, let me know 👍🏻