I don't think the Meraki agent can be "managed" because it's not uninstalled when you remove the device from systems manager. My understanding is managed app's are app's that are provided via VPP only.
You can only push software packages to MacOS devices if the agent is installed, the profile alone does not allow you to install packages from my understanding. The exception to this is the SM agent I believe.
Are your devices enrolled via ABM / ASM or are you enrolling them manually?
Try re-enrolling an affected device to see if it fixes the problem.
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