What's the meanig of 'not lost on me' in the second last sentence?
No one helped Frankie when he needed it. And so he went on to cause mayhem in his family and, on one alcohol-sodden night, to murder a man. My mission is now to help the person who bullied me, who caused me years of grief. It's not lost on me that the balance of power between Frankie and me has shifted. Frankie has no possibility of parole.

Thank you.

Question

What's the meanig of  'not lost on me' in the second last sentence?
No one helped Frankie when he needed it. And so he went on to cause mayhem in his family and, on one alcohol-sodden night, to murder a man. My mission is now to help the person who bullied me, who caused me years of grief. It's not lost on me that the balance of power between Frankie and me has shifted. Frankie has no possibility of parole. 

Thank you.

Answer

'To be lost on' can mean either a) to have no effect or influence on someone. " Her tears were lost on him." = he wasn't affected by her tears or b) to not be understood by or beyond the comprehension of someone. " His explanation was too technical and lost on us" = We didn't understand his explanation because it was too technical. 
The negative 'To not be lost on' as in your example therefore means to be understood by or not beyond the comprehension of someone. 'It's not lost on me' = I have understood.

Answer

lost on me = lost to my awareness

It's not lost on me = I'm well aware of it.

Answer

"It's not lost one me" means "I understand that..."