Hi Bert,
I am not sure of what might be causing this strange behavior without a working sample. I have tested this issue in a simple application with Essentail XlsIO V.5.2. But i was not able to reproduce the issue. I have attached my test sample.
http://websamples.syncfusion.com/samples/Grid.Windows/38539/main.htmIs it possible for you to upload us a minimal sample or modify the attached sample to reproduce the issue here? This will help us to analyse the issue further.
Thanks for using Syncfusion product.
Best regards,
Haneef