I am also using Studio One Pro 6.5. My BIAB plugin says it is 2024 version 6.0.7. If I remember right when I first got the 2024 version of BIAB the plugin did say it was 2023.
When I create a new song in the plugin and render it and drag it into S1 the drums and all tracks are there to the end of the song. I am not seeing what you are seeing. Am I missing any of your steps?

Brian

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BIAB 2024 Ultrapack- Studio One Pro 6.5 Windows 10