Easy Chart Tag Plotting Not Showing History

I have an easy chart that is connected to tag history. Sometimes it works correctly and nothing goes wrong, but other times I get the following plot where that long line jumps all over the place as the tag changes, but the point isn’t actually plotted on the graph and the line just gettings longer and longer.

I should point out that I am using Manual Chart Mode in combination with a separate time range filter at the bottom, so that I can plot real-time data with a timeframe controlled by the user.

What can I do to fix this? Is this is bug? Is there an alternative?

What is happening here is that the system is not reading any more historical data, so it keeps drawing a line from the last historical point to the current value.

This could be caused either by logging not working or by the mechanism you’re using to read the data not working - I can’t tell any more without more information.