Hi James,
Thanks for using Syncfusion products.
I am afraid that I am not able to reproduce the issue, you have mentioned here. The visible property of the GridControl is working fine for me in RecordExpanded event.
Please refer the video clip from the below link, which illustrates the above:
http://www.syncfusion.com/support/user/uploads/expand_c7ffd221.zipPlease refer the sample from the below link which illustrates the above.
http://www.syncfusion.com/support/user/uploads/Expand_5836335b.zipPlease try the above, if still the issue exists, could you please send us a simple sample to reproduce the issue? so that we could sort out the cause of the issue and provide you a better solution.
Regards,
Raji