Apologies for taking so long to reply.
OS: Windows 10 Pro version 1607 build 14393.447
Avast version: 12.4.2281 (build 12.4.3256.0) using virus definitions 161114-0
Network setup: PC connected via ethernet cable to router/cable modem.
Using Private Internet Access for VPN.
Popup happens before VPN loads so that is ruled out. Has to be a Avast beta bug.