This is actually pretty interesting.

On June 30, its first drug-manufacturing experiment succeeded in growing crystals of the drug ritonavir, which is used for the treatment of HIV, in orbit. The microgravity environment provides some benefits that could make for better production in space, overall reducing gravity-induced defects. Protein crystals made in space form larger and more perfect crystals than those created on Earth, according to NASA.

Unfortunately there's no info on why it's being denied reentry. (But my money is on the long standing secret policy of the dark world government lizard cat people to not cure space aids)(I also don't have any money)