Hi Jens,
Thank you for using Syncfusion products.
Regarding your query of using the isBusyProperty to indicate an activity when datasets are loaded in the grid, SfDataGrid has been programmed such that setting values to IsBusy property loads an activity indicator only in scenarios of PullToRefresh
However your requirement can be easily achieved in the sample level by loading a activity indicator and changing its IsRunning property in the GridViewCreated event handler.
We have prepared a sample based on your requirements where we have displayed an activity indicator till the one lakh data sets are loaded into the grid. Please find the sample from the below link.
Sample Link :
http://www.syncfusion.com/downloads/support/forum/123772/ze/GridBusySample769347879Kindly revert us if the sample meets your requirements or in case of any queries.
Regards,
Vimal Prabhu