I've been searching to find out what happened and thanks to a couple of Reddit posts, I think I know what's going on.

This line of buildable figures wasn't that popular. Apparently figures of droids and masked characters sold the best but the general consensus was that figures with human faces just looks odd.

But despite Jyn Erso's figure being officially retired in April 2018, even as late as last year, people are still finding boxed copies in stores. It just didn't sell.