Blu-rays not playing?

Hello! First time poster to this community, but a long time collector of physical media!

I have a large collection of movies on DVD and Blu-ray. The disc player I use is a multi-region Sony Blu-ray player BDP-S1700.

Recently I have been getting error codes with some of my discs, specifically my Blu-rays, saying unreadable disc, check for scratches. I cannot see scratches. I've tried all the methods online to clean the disc and fill any scratches. I tried the bananas method. I tried one of those wax pencils made just for scratched discs. I cleaned them carefully with diluted isopropyl alcohol. The discs in question are discs in a set: Twin Peaks the original series, Twin Peaks the Return, and the Twilight Zone. Only some discs are reading with the error. I even had my boyfriend dust the inside of my disc player and check that the lazar was clear. I really cannot afford to replace these sets.

Is it my disc player? Is it the Blu-rays?? Do you have any tips? Has this every happened to you?