Hmmm, well that complicates things. And when you say 'open your startup file', are you doing that by going to File > New > BLUI 0_7_5?
The Right Mouse Navigation got moved out of the App Template, and into its own separate addon: https://github.com/SpectralVectors/RightMouseNavigation, it was called UnrealRightClick until a couple of days ago, so some of the old links may need to be updated, but the one I just pasted here is current. I did it this way so that you can use it with or without the rest of the template.
I hadn't been actively developing any of my projects for months before this last week, when I got a few messages about bugs with Blunder. I'm trying to polish a few things up now, fix some bugs, and hopefully cobble together some kind of user guide so that there's a little more for people to go on.