What do you see on the Performance Chart if you set the Aggregation to None (raw/unintervalized data)?
Performance Reports Designer can use either raw (unintervalized) or intervalized data. For intervalized data, a data aggregation interval is automatically selected based on the scale of the chart you are viewing. You can also choose an aggregation interval for the chart. Possible intervals range from one minute to one day.
Note: The unintervalized data option ("none") replaces the raw data option in Performance Reports Designer in CA UIM 8.47 and later.
For an automatically selected interval, the timeframe of the data and resolution of your screen affects the scale. Performance Reports Designer selects the smallest aggregation interval so that there is only one data point per pixel. If there are multiple data samples for an interval, the values are averaged. For example, if the data is sampled every 5 minutes but the Performance Reports Designer chart is displaying 15-minute intervals, there are three data samples per interval. In this case, the average of the three data samples is displayed in the chart.
If you look at the values collected for these devices in the RN_QOS_DATA tables for the QOS_AVAILABILITY_AVAILABILTY metric over the displayed time interval, do you see any values other than 0 or 100?