Added FB mediation with admob but no ad's show

Question

I have all validated

admob account OK
grpd OK
integration of admob on my flutter app OK
mediation on admob OK
creation of account on facebook audience network  OK
creation of property and location OK
validation of app by FB ok 
validation of app-ad.txt by admob and FB OK

My app receive a limited match rate ad from admob but nothing from FB mediation

On (FAN dashboard) my property seems not finish

step 1 (app details OK)
step 2 (app payment account OK)
step 3 (app verification OK)
step 4 is Intégration du SDK, I select admob and clic on finish but the badge not change to green check

I have this message : Waiting for bid request

what I need to do ?

I have also well add on gradle dependencie

implementation 'com.google.ads.mediation:facebook:6.16.0.0'
implementation 'com.google.android.gms:play-services-ads:22.4.0'

and also add on the manifest

android:networkSecurityConfig="@xml/network_security_config"
network_security_config.xml

and on res/xml/network_security_config.xml

<?xml version="1.0" encoding="utf-8"?>
<network-security-config>
<domain-config cleartextTrafficPermitted="true">
<domain includeSubdomains="true">127.0.0.1</domain>
</domain-config>
</network-security-config>

I need to add flutter_facebook_audience_network package or com.google.ads.mediation:facebook:6.16.0.0 is enough ?

I just found this debug function on FB but I don't understand what I need to do

thank you