If you could, please provide some details as to what you mean "does not work." That could mean a lot of things. Also provide a list of any exotic 3rd party plugins you might be using.
I have no issues at all with Multi/SubObject and didn't with 2024.1 either.
Edit: I went to explore. I think you might be saying that the 'Show Shaded Material in Viewport' button does not function. Is that correct? It doesn't function in 2023 either. It might be the way it's redesigned to work now for some reason. You can alway back up and turn it on for the Material that is being piped into the specific ID. It works fine there.
Edit 2: This intrigued me so I explored more. It's not broken. That's how it's always worked, at least since 2010 anyway. Here's a post that talks about it that is helpful:
NukieFrequenter Nov '10
Multi-sub object isn’t exactly a material but more a basket to hold more than one material. So it shouldn’t be treated as a material. Therefore you wont see a “show map” button. As said you have to go into each separate material inside your multi-map material, and there you will find the button your looking for.
In addition, if you have a lot of materials and do not want to go into each of them. You can go to the “Material” menu button on your material editor, and you will find the “Show materials in viewport as >”. There you can select how you want to display your materials. This, however, toggles all the materials in your scene so be careful with it since it takes a lot of memory if you have a lot of materials.
https://forums.cgsociety.org/t/how-can-i-see-my-multi-sub-object-material-in-my-view-ports/1473651
Rob Holmes

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