It appears that in Android (and iOS) the menu button (see images below) will be covered by the 'Back' button when there is at least a page on navigation stack. To bring up Masterdetailpage again, I have to click 'Back' (multiple time depending on how many pages on stack).
The same issue does not occur in UWP, where the 'Back' button and the menu are in different rows.
I wish to maintain navigation stack and, at any time, access the masterdetail page. However, with the menu button hidden (covered by 'Back' button) it doesn't seem to be possible until you clear the stack.