Right, I now see you're in a PM role. I think the decision on where people work from should lie with their line manager ("unless required by the project") and it's the line manager that should evaluate productivity. The PM should of course give input if a developer doesn't manage to close out tickets etc - but the line manager is the one that should have regular 1on1 talks with their employees.
I found that just sitting down and talking to my people for half an hour (without a set agenda! talk about anything) a week did wonders - both for their experience of "being seen" at the workplace and my understanding of what if anything was hindering them from doing their best.