I have installed Brave Nightly on 3 Android devices:
1)Dev1: Android 5.1.1
2) Dev2: Android 8.1.0
3) Dev3: Android 7.1.1
Setting Up Sync works for Dev1 & 2.
When I try to add Dev3 and I tap >Synchronize, the window for scanning the QR code does not pop up - the browser just reload the previously loaded web page.