Hi Adrien,
Thanks for your interest in Syncfusion Products.
I'm afraid that I was unable to reproduce the issue while handling OLE Drag&Drop between two grids in OLE Drag-and-Drop Demo sample shipped with Syncfusion Dashboard v7.2.0.20.
Here is the sample attached for your reference.
http://www.syncfusion.com/uploads/redirect.aspx?&team=support&file=DragAndDropFromSampleBrowser-874020949.zipPlease try to reproduce the issue in the attached sample, and provide us. So that, we can see the issue and work to provide solution.
Regards
Ranjeet Kumar