Taming can be a really tricky and long process for some hamsters; just depends on their personality - my current shy Syrian baby is taking a lot longer than my previous more curious and outgoing Syrian. They do sometimes go through a spook period again during taming, but all isn't lost and you will get there!
A couple of ideas to try... hamsters aren't keen on overhead lights or bright white lights; you could try a dimmer, more mellow lamp in a corner of the room. I have mains operated fairy lights over a bookcase in the room where Wintergreen lives, and the mellow glow they give doesn't usually deter her from peeping out, unlike the room's main recessed spot lighting. There's still enough light to see her though!
Another thing to look out for is scent; hamsters hate us having other odd smells on our hands, so it's a good idea to wash them thoroughly with the same soap each time you interact. If you haven't already tried it, you can also take some fresh bedding, and rub it on somewhere like the inside of your elbow or neck (weird Ik but it's got to be somewhere that will carry your scent more strongly...!!), then pop it in her cage nearby her nest. She can then nest with it, and get used to your scent being associated positively with her secure cosy bed.
Hope that helps!
p.s. did notice you'd mentioned using a ball to get her out in... not sure if you mean something else or not, but hamster balls for rolling around in aren't good. Ik they're sold in pet stores etc., but they're cruel and dangerous for hamsters. Here's a great explanation of why:
https://www.youtube.com/watch?v=K-78oX2R0eo A coffee mug with a treat to encourage them inside is a great way to lift a hamster out of their cage, and you can work at petting them inside the mug first, before even taking them to somewhere safe like a bathtub with a blanket in the bottom for further taming and handling practise.