I would stop the flakes as your fish and inhabitants deserve better. Something like LRS nano is about 1000000 times better for all.
I am not saying this is related to your problems... more or less trying to prevent you from finding new problems later.
I have many thriving torches but can’t say I do anything special for them. They are under bright lighting, moderate flow, I do not feed any coral foods and po4 and no3 wax and wane. I feed the fish heavy with good healthy foods and dose 2 part and that’s about all I do.