Hello Taqi,
Thanks for your interest in Syncfusion products.
Regarding your query, I was not able to reproduce the issue. I have tried adding/editing values in the gridDataBoundGrid that uses Dropdown cell type and it was working fine. I have attached the sample that I have used for testing with this post. -
http://websamples.syncfusion.com/samples/Grid.Windows/F64509/main.htm Please have a look at the above sample and if still the issue exists, could you please try reproducing it in the above sample or send us the reproducing steps so that we could sort out the cause of the issue and provide you a solution?
Thanks,
Meera.