Hi Andrew,
Thanks for choosing Syncfusion product.
We are not able to reproduce the issue.
Please provide us with some more information it would be easy for us to identify it quickly and get back to you.
I have modified the sample to get the size of the annotation before constructing it.
Let me know, If you have any queries.
Regards,
Sujitha S
ChartSeriesAnnotaion_f7981419.zip