I can not add any type of control to the layoutControlGroupItem. I have a screen recording of me trying to follow the procedure shown but it is 60M so I can't attach it. I shared the file on my OneDrive if you would like to access it that way.
Hello, Jeff,
The provided sample video is greatly appreciated. Indeed, I confirm that you can't drop a control onto a tabbed group:
After further research I have noticed that it was broken in R2 2018.
I have logged it in our feedback portal by making this thread public. You can track its progress, subscribe for status changes and add your comments on the following link - feedback item.
I have also updated your Telerik points.
Currently, the possible solution that I can suggest is to add a LayoutControlGroupItem first and then add the control you want in it. Thus, the group item can be added to a tabbed group at a later moment.
Regards,
Dess | Tech Support Engineer, Sr.
Progress Telerik