RadRibbonButtons are designed not to get the focus when they are clicked. Setting the IsTabStop property to True is one of the correct ways to allow them to get the focus.
I guess you are testing the events with break points in Visual Studio. Note that when the IsTabStop of the button is False the LostFocus property of the controls placed inside your form should not be fired. However, when the break point in the button's Click event handler is hit, VS is getting the focus and this is why the LostFocus event handler is fired.
This same behavior is preventing the click of the button to be executed. Your application lost focus when the break point hits and the click is never called.
You can see that the events are fired as expected in the attached project (in the Visual Studio's Output window). If this is not your case and the issue still occurs I would ask you to send us an isolated project that demonstrates it. This will allow us to test it locally and investigate what stands behind the reported behavior.
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