The most common cause of missing data on the dashboard is that the view's project universe (A) is missing some projects. To fix this, click to update the view (B) and adjust the project universe accordingly (C). For example, make sure that all projects are selected, or understand that a filter may be excluding some projects by design.
IMPORTANT: For completeness purposes, Utilization and Availability views "ignore" the selected project universe and automatically include all projects. Projects outside of the project universe are displayed as "Other". If a resource's Utilization or Availability appears to be missing some projects, confirm if the project is excluded from resource forecasting calculations.