We have noticed a problem when a chart is in realtime mode that when you increment the time, whether it is minutes or hours, the chart display displays differently as you increment the number from 1 to 2 to 3 etc up to say 20. sometimes the traces fill the screen and sometimes they don’t reach out to both sides of the chart. If you can’t duplicate this in your lab I will be glad to show you in applications on line. All of these problems still appear in 7.5.2 and 7.5.3 beta.
Did you check the database to see if there were times where data is missing?
Are these charts set to -1 resolution? If so, they’ll only chart what happens to be recorded during that time frame, which may not include any data.