I know a lot of people found the characters flat and one dimensional or having no chemistry, which I totally get. It does come off as forced at times, and I'm still an it baffled as to why they cast some amazing actors only to underuse them.

So I think the lack of characterization and chemistry has led to lack of fic and interest. The first time I watched it I did t really come away wanting to see more of any ship because they told their stories and wrapped them up nicely. Even Cassian/Jyn didn't feel romantic to me, but I don't think that's what the movie was going for anyway.