Hi Rob,
Greetings from Syncfusion.
We have ensured your reported scenario; chart series data
points values are displayed properly after editing the value. We have prepared
sample based on your requirement. Please check with below screenshot and
sample.

Sample : https://www.syncfusion.com/downloads/support/directtrac/general/ze/DataEditing402163856.zip
Since we are unable to replicate an issue from our end, we
request you to share the following information which will be helpful for
further analysis and provide you the solution.
- Try to reproduce the
reported scenario in attached sample.
- Please share your sample
(or) code snippet with full configurations.
- Share the details if you
have done any other customization in your sample.
- Share your datasource
file.
- Share your nuget package
version.
Kindly revert us if you have any concerns.
Regards,
Durga Gopalakrishnan.