Testing an Action makes it available for the account which activated the test. It does not make it available for every account on a device - Actions do not load anything on the device itself, they simply permit the account to the trigger commands on Google's server.
If you want other users on the device to access the Action, you need to explicitly permit them to the action. You can see the details, or they're listed if you click the share icon in the simulator, but in short:
Click the gear in the upper left of the console and then the Permissions menu item.
Add team members to the project using the Add button on the top. I usually give them Editor or Viewer project roles.
They then need to visit the simulator page to activate it. They can use the simulator to test, but it is also available on their devices.