The Stimulator Settings (found under 'Setup' --> 'Stimulator') in the LabTutor Kernel have settings that are affected by the corresponding Stimulator Panel Page Item within the LabAuthor Interface.
The issue above is caused by having the 'Require Isolated Stimulator' checkbox in the Stimulator Panel Page Item Properties (right-clicking on the Stimulator Panel Page Item and select 'Properties') checked. This box is checked by default when creating the Page Item for the first time:
This setting configures the Stimulator in the LabTutor Kernel to only be usable with an Isolated Stimulator attached. To enable the use of the Analogue Outputs, ensure the 'Require Isolated Stimulator' checkbox is unchecked. This will allow the Stimulator to be turned 'On' when in Analog Output Mode: