Aquariums: Angelfish not eating

Need advice as first angelfish owner.

2-3 weeks ago I got two marble angelfish which first week acted fine, but then one of them stopped eating flakes while other eats fine. I thought she was picky or getting bullied by my terrorist gourami, I tried giving her bloodworms and removing gourami but it didn't work. She hides in the open corner and occasionally goes out, especially when lights go on or when I approach fish tank. Shows interest durning feeding times but as soon as she sees flakes goes back down

Water seems fine, temperature fixed to 27 Celsius
Should I try new food or treat from something?

(Sorry for English, not my first language)