We have ZMM V3.1.0 in a school

I've begun experimenting with Apple's VPP
I've downloaded the token and uploaded it into ZMM.
I purchased an App using the managed option with 20 licenses
I went to APP management in ZMM and synced with VPP.
The app did not automatically appear. Should it have?

So I added it manually and synced again. Now the 20 licences are tagged to the app.

I've applied the app to devices but it is not installing. If I look in the agent, "managed apps" it is listed there with "required" greyed out.

If I look in ZMM reporting. app reports to users, it is listed there with Not managed by MDM.

I am stumped.