Undo method in TAdvMaskEdit

Hi Support.
My Delphi is 10.3 (Rio) Update 3
My TMS Component is
TAdvMaskEdit, version 4.0.1.2
I do have problem with the component method "Undo"
When I have no mask (i.e. as a normal TAdvEdit), and I modify the content and execute the "Undo" method, it works.
However, If I define a mask ("!99;1;_"), and I modify the content and execute the "Undo" method, nothing happens.
Any suggestions?
Br.
Anders