My company uses Teams and Skype.
User reported that she's available on Teams and Skype but on Outlook 2016 she appears away (white box instead of green box).
I had to do some digging and research to find out this is an existing bug.
Below are the changes I made in registry.
Green box appears next to users name in outlook when user is working. Hope this helps everyone.
Change default value to Teams.
Once you update, restart machine.