Dynamics NAV - Users cannot see any companies

User Access Control table is missing user permission set assignments.

Insert records here to assign permissions to users.
Use the powershell commands here

https://docs.microsoft.com/en-us/previous-versions/dynamicsnav-2013r2/jj672890(v=nav.71)

From powershell or administration shell, run as administrator
New-NAVServerUser MicrosoftDynamicsNavServer -WindowsAccount Cronus\Chris

New-NAVServerUserPermissionSet DynamicsNAV71 –WindowsAccount cronus\chris -PermissionSetId BASIC

New-NAVServerUserPermissionSet CRONUS –WindowsAccount cronus\Joe -PermissionSetId SUPER


eg.
New-NAVServerUser BC150 -WindowsAccount mypc\test New-NAVServerUserPermissionSet BC150 –WindowsAccount mypc\test -PermissionSetId SUPER