[mhomyack]

So, it turns out that it was that the Quest Helper had become unselected. The odd thing was that the checkbox also seemed to be greyed out, such that I could not re-select it at first. However, after toggling through the tabs on the Quest Journal and back to the tab where you can enable the Quest Helper, it was again enabled and I was able to re-select it. All now appears to be well.

Thanks for the input!