According to the author of the question, the problem only occurs if these two situations occur simultaneously:
- The form is set to start maximized;
- Maximize button is disabled, i.e .:
this.MaximizeBox = false;
This is done through the IDE, which underneath the wipes generates the code snippets present in the question and in this answer.
I tested and was able to reproduce the behavior in .NET 4.5 with Visual Studio 2013. Forms that do not have the maximize button enabled, when maximized, are behind the taskbar.
I believe that maximizing something that can not be maximized is absurd, and forcing the user to use an application that occupies the entire screen - especially if the interface components do not need it - should not be encouraged. My suggestion is to apply a minimum size to the form if necessary, but do nothing else with regards to size.