Deployment for software not picking up already compliant devices

Hi Everyone,

We are in the middle of deploying a new SCCM environment to replace our old one and i'm in the currently redeploying a lot of the applications to user collections. I'm finding that deployments are not automatically identifying machines as already compliant even though i know certain software at the correct version already exists on the machine.

My question is:

If a users device already has a piece of software installed, regardless of the method it got there, why doesn't my user deployment for the software report back machines that are already compliant?

For clarity, this is simple MSI deployment that has been made as an AVAILABLE installation to a user collection. And yes, the detection methods are solid etc.

The deployment monitoring literally returns nothing even though i know there are at least 5 users with that software already on their machines and the detection criteria should be picking this up. When one of the users clicks the install button in software centre for the software it doesn't try to install it and just detects it as it should. Only then does the device show as already compliant in the deployment monitoring for the application.

I'm pretty sure this is by design, but i don't understand how you're supposed to get a user based deployment to pick up existing installations. Making it a REQUIRED installation would likely give me what i want reporting wise, but i don't want this software auto-installing for everyone.