Falcon's permissions system allows numerous settings. To make sure that you have assigned the permissions as required, you can view the project tree from the perspective of each user.
To do this, first go to the Permissions tab in the Hub Management (cogwheel icon in the lower right corner of the sidebar).
Right-click on the desired user and select "Check permissions".
Now you see the tree from the user's point of view with the respective right
Alternatively, you can click on the user icon on the right above the project tree and check the permissions of the users one by one.