@lostfrogg: as @radzmar says, the master page is not the best location for such things. To explain the behavior of the object a bit more:
The master page is a normally a static backdrop for the surfaces (pages) where you define the areas of content (that you can then place in page subforms) and things like the page numbering and fixed footers etc etc. When there are layout changes in dynamic forms, the master page instances get re-rendered and everything falls back to the designed state.
When you go and use the .presence="" on a master page object in a script you may see it appearing when in interactive mode in the Reader. But everytime there is a re-render taking place the object falls back into its original state. That might also happen when you open that PDF again later.
You would have to use scripting in the master page object to determine its initial state based on something in the data and that must execute every time the master page is re-rendered (initialize).
Give us an idea of what you want to do and why.