To reproduce:
1. Add a RadStatusStrip at design time.
2. Add a RadWaitingBarElement at design time.
3. In the Properties section of Visual Studio set the WaitingStyle property to DotsSpinner. You will notice that the WaitingStyle is not serialized. If you run the application the default WaitingStyle is displayed.

Workaround:

Set the WaitingStyle  programmatically at run time.