Your paid LR subscription via Android should also provide Premium sync service on iOS. Please confirm you are signed into Lightroom with the same email ID on both devices? If so, does it help to sign out and then sign in again?
If that is no help, please sign into your account at lightroom.adobe.com -- do you see a "Sync Issues" album there? If so, confirm you have copies of the image(s) saved on your device camera roll, then delete the image and import it again. Does this help? DO NOT delete the image before confirming you have a copy saved somewhere outside of Lightroom.