The Dynamics GP Support and Services Blog has a post on the missing security in Microsoft Dynamics GP 2018 RTM; this is the new security roles and tasks created for the new functionality.
For features which are being enhanced, the new security tasks may be being added to roles which already exist and are assigned to users, the security is not automatically updated with the upgrade, but instead scripts are made available to add the missing security; this places the onus on the client to determine if the roles should be updated or not.
I have updated my original post with the new script, but you can also download it here.