Storyline: HTML5 Course won't play because of Flash?

Hello,

I built an HTML5 course a couple of years ago using Storyline 3. The course stopped working not long after December 31st, 2020. I knew that most browsers would end support of Flash and so I published the course in HTML5 to avoid this problem.

Given that the course doesn't work anymore, I decided that it would be best to rebuild it. When I went into the Storyline Player Properties window, I found an odd Flash message (see attachment). Has anyone else seen this? What's the recommended approach to save my content and eliminate future problems with Flash?

Storyline version: Update 5: 3.5.16548.0