NearbyConnectionsWalkieTalkie : Huawei P8 Lite under Android 7 advertise not seen by others

[dvr69]

I'm trying the NearbyConnectionsWalkieTalkie sample on two phones, a Huawei P8 Lite under Android 7, and a Huawei Mate 20 Pro under Android 10. The automatic version works fine. For the manual version, when I shake the Android 10 phone (the advertiser), the Android 7 (the discoverer) connects to it. But when I shake the Android 7 phone (the advertiser), the Android 10 phone (the discoverer) can't connect. Is there a reason for that ?