The font used to report upload/download speed in the menu bar is called "Apple LiGothic". This font can sometimes become inadvertently disabled, which results in upload/download numbers looking like this:

The fix for this is simple:

  1. Open the Font Book app (simplest way: type "Font Book" into Spotlight search and hit Enter)
  2. Type Apple LiGothic into the search field.
  3. Select Apple LiGothic > Medium in the font list.
  4. Choose Edit > Enable "Apple LiGothic Medium" from the menu.
  5. As soon as you do this, PeakHour's upload/download menu bar display should render properly: