Bake to OCI with multiple images

With a compose file

services:
  service1:
    build: services/service1
    image: service1:0.0.1
  service2:
    build: services/service2
    image: service2:0.0.1

I want to bake this into a single OCI tar file, containing both images with

docker buildx bake -f docker-compose.yml --set="*.output=type=oci,dest=out.tar"

This builds fine, but the resulting OCI tar file never contains both images, always just one. (The resulting manifest.json list only has one entry.

Is this unsupported, or am is there something wrong?

With --load, both containers get loaded fine to the local docker, and I can then save those again with docker save service1:0.0.1 service2:0.0.1 > out.tar. This produces a correct image with two entries. However, it would be nice if we could directly build to the OCI image.

Reproduce the provided docker buildx bake command with the two-service compose file and inspect how OCI output handles multiple bake targets. Done means the resulting out.tar contains both images, with two entries in its manifest.json, rather than only one.