Audio track modification in multicam clip

Hi,
On a multicam clip, I have modified some audio samples with fairlight on one of the audio track because of scratch noise. But after flattening my multicam clip, audio track (same one) has no more modification.
How to keep multicam modification after flattening
Thank you for your help
Regards

DaVinci Studio 19.1.4

Flatten first, then do the audio work.

Flatten first, then do the audio work.

Thank you for answering
I noticed that I must open multicam in timeline before any modification on video or audio track. When I come back to multicam clip, modification is taken into account
Then, I can make my assembly and flatten it
Have a good day