Hi Paul,
Thanks for your interest in Syncfusion products.
I am afraid I am not able to reproduce this issue. I have attached a basic chart sample which displays the Stacking Column and Column chart in 3D. Could you please try running this sample at your end and reproduce the problem in sample and send it back to me so that it would be easier for me to find out the solution at the earliest?
F44468.zip
Also please let me know about the version of Essential Chart in which the problem occurs.
Regards,
Geetha