Can't perform multi-platform build from docker compose with cloud builder

I have successfully built an image for a multi-platform image via docker compose locally, when I run the same compose command with --builder=cloud-xxx-xxx I get the following error cloud pull for multi-node builds currently not supported.

the docs for cloud builder claim that mutil-platform builds are supported and I I can find no information on the error. Any ideas? We would really like to be able to build multi-platform images via the cloud builder, it is one of the main reasons we signed up.