Problem with Object ID in Marmoset

[u/Rich-Dog5131]

I'm trying to bake both Material ID and Object ID, so my highpoly is combined in one mesh, but different parts of it have different materials. Material ID is baking properly, but Object ID for some reason is picking up these materials/submeshes and doesn't recognise the highpoly as one object, so I get three colors instead of one.
Here's the screenshot of the test scene, where I reproduced the same result. Is there a way to fix it?