Hi all,
I posted a solution to this issue that requires a simple edit to a function in the "scormdriver.js" file in the published Rise package on this thread:
https://community.articulate.com/discussions/rise-360/blank-screen-after-update?page=4
Making this fix whenever you update a course will not not delete learners' progress. What it does to eliminate the blank page on restart issue is that it does not load the bookmark on restart - the screen/page where the user left the previous session. So it always launches the course at the opening screen, but the lesson/topic progress markers in the left-side menu and all learner progress are retained.
Hopefully Articulate will build a similar solution into Rise ASAP.