I don’t know what to think. Other than long fiction just doesn’t do well on Medium. People don’t seem to like long stories (over 6 minutes) or parts (unless each part stands alone.)
I think part of the problem is the lack of an in-story bookmark in Medium. I rarely tackle a long story for that reason. I read your Movie Stars And Planets but I didn’t look at the length before beginning and read it in two sittings. If we could save our place in a story it might help. But who knows?
I have published fiction in many length. One 20 minute story got 2 reads. A 14 minute story got 1 read. A 12 minute story got 3 reads. I have have also published 50 minute story in 14 parts and it averaged 3 reads per part. A 30 minute story in 5 parts did about the same. Maybe it speaks to the quality of my fiction. But the few who did read it left good comments.
An 8 minute story I published in LitUp did well. As did shorter fiction I posted there. I think fiction published in a publications does better.
I have never had a story curated in the new Fiction category by Medium. I am sure that would make a difference.