ProRes 4444 didn't work

I solve it!

The problem is..

the clip contains not only chroma key part but some other b-roll as well

so, I edited it with only chroma key part, and export PR4444

SOLVE IT!

I have totally no idea why it happened and why it solved

Thank you for helping me!

1. this is file information that i got from my friend

it is PR422 LT and there is green screen

2. this is information after I used 'keyer' effect

Though it is black, I can change background with any images

idk why it is black even though I set it checkerboard

3. this is sequence setting

4. this is information after reimporting file

there is checkerboard in background

and codec is PR 4444

5. this is sequence setting

I tried to rendering with PR422 and PR4444 both

but nothing changed

6. I put solid blue in background but not affected

Plz help me 😟

Yes, I tried to do color correction with Davinci.

As I change level of this clip, I saw background became brighter.

So, I tried to reimport it to final cut pro X, and I knew there is no alpha channel