This is separate to Dashingdon, and can be fixed by including an *ifid command when compiling the game - there’s info about that here.
With an *ifid command is in startup, the game will keep progress even if the tab is closed or navigated away from.
I’ve edited the title of the topic to describe it more accurately so people can find it if they need to in future (personally, I’ve forgotten it a couple of times!).