I just had a problem with this topic and wanted to share my experience.
In Apple Business/School Manager there are two App sections, AppStore and customized (B2B) Apps
In a first step, we've been able to sync the customized App through our VPP token and everything went fine. Now some days ago we force synced the VPP account and the customized App changed it's name to "Unknown (adamId xxxxxxxxxxxx)"
After contacting support, they activated a feature on our backend so we gained the ability to add such Apps manually now.
Currently it seems to work, but I'm wondering why this approach, why did the behavior changed and why there is nothing to find about it in the docs? @Noah_Salzman@Kevin_C