I am having the blank screen issue only with some learners too. My Rise course was updated and the SCORM zip file replace several times, but all of that occurred BEFORE any learners were assigned. It occurs regardless of browser, and I am able to recreate the issue on these specific user accounts when I emulate the learner using our "login as" feature in our LMS.
It has also occurred when a learner exits the course before completing it and attempted to resume the course.
I found that deleting the user's scorm attempts resolves the issue. Hoping you have a solution.