Hi Tom,
The cell shows a blank value. I have prepared a sample to test the issue and it is working fine as expected. Please refer the sample.
http://www.syncfusion.com/support/user/uploads/GDBGGridListControl_6af7d029.zipPlease have a look at the above sample and if still the issue exists please provide a sample that shows the issue. So that we could sort out the cause of the issue and provide you a solution soon?
Regards,
Jisha