Question: Why are screen objects such as the red line marking the current day in the Gantt chart, or the capacity lines in the histograms, not displayed (correctly)?
Answer: If your browser's zoom level is set to something other than the default, it might result in odd rendering of thin lines such as the red line marking the current day in the Gantt chart, or the capacity lines in the histograms. You can restore the default zoom level using Control+0.
If your capacity lines in the histograms are missing, make sure you didn't select the option Filter Allocations in Histograms by Selected Projects in the Portfolio Designer Settings.