I doubt it's the calcium, do they also have access to grit? Grit is crushed granite, sold as poultry grit and it's needed so they can grind up and digest food in the gizzard. The calcium (crushed oyster shell usually) is needed as they use it making egg shells, but they both serve very different purposes. The calcium is soft and will be absorbed. Both should be available in separate feeders all the time. Some environments have enough small stones around that they find and use those, but it's a good idea to have the grit available in case it's needed.
Massaging is not a problem as long as you don't push the contents of the crop up and into the esophagus where they might aspirate it, so massage in a downward motion, or side to side, not pushing up. I would continue to do massages to try to break it up. The oil also shouldn't cause a problem. You can try mixing some into the moistened feed if she will eat it that way. If she's got grit, and it's still not clearing, then she may have something else going on. Reproductive problems are not uncommon, she's a bit young but it's still possible. Those can slow digestion and cause crop back ups. Time will tell on that. I would keep an eye on her, check her abdomen for any bloating that might develop (below the vent between the legs). There are a lot of causes of crop issues and the problem is most often not the crop, that's just the symptom that shows. Unfortunately the ultimate cause is not known until they pass and a necropsy is done. I've had crop back ups from worms, reproductive cancers, salpingitis, an impacted gizzard in one case. I've never had a bird with hardware disease, but that can also be a cause. She's passing some droppings, so that is good, whatever is going on hasn't completely blocked her.
More crop info here, might be helpful:
https://www.backyardchickens.com/ar...ntion-and-treatments-of-crop-disorders.67194/
https://www.backyardchickens.com/ar...w-to-know-which-one-youre-dealing-with.73607/