This behavior occurs when there is no Telerik package installed in the project but the toolbox loads the controls using the version available in C:\Program Files (x86)\Progress\ToolboxNuGetPackages.

Then drag a gauge form the toolbox and drop it into the form:

To reproduce: the purpose is to have only one label with at a specific value. Hence, you try to adjust the start/end index of the labels and according to the labels count, you get the desired result. A similar approach is applicable for the ticks, but it hides all labels when you try to set a value for the LabelEndVisibleRange .