WooCommerce Product Out of Stock

My WooCommerce product for my course on CoursePress is changing to Out of Stock. Even when I go to change it back to In Stock, it remains Out of Stock.

I'm not sure how to fix, and I'm not too tech-savvy so any feedback/support you can provide is very helpful.

As was referenced to in other threads, my PHP version is 7.0.16.

Please let me know how I can help,
Alex