Problem with connection from android phone to IPv6 endpoint

[Ryuichiro Nagasaka <r.ngsk.todo@gmail.com>]

Hello,

After upgrading Wireguard Android app to v1.0.20200724 by Google Play Store,
The wireguard connections with multiple hosts via IPv6 network failed
to establish.
Using IPv4, the connections had no problem. Also, the ones from iPad including
IPv6 were good.

Before the upgrade, the app version was V1.0.20200407, which could establish
connections successfully.
# reconfirmed by manually installing the old version of the app.
# The IPv6 internet connection from my phone is always quite good.

On my router, I used tcpdump to check whether packets emitting from my phone
were observed. But, no packet was found.

Android Phone's configuration (Zenfone 6):
=============
[Interface]
Address = 10.xxx.y.z/24, xxxx:xx:xxx:xxxx:yyyy:y::z/96
PrivateKey = (hidden)
DNS = 10.xxx.y.1

[Peer]
PublicKey = (hidden)
PresharedKey = (hidden)
AllowedIPs = 0.0.0.0/0, ::/0
Endpoint = [xxxx:xx:xxx:xxxx:yyyy:yyy:yy:y]:1194
==============

Router's configuration on /etc/wireguard/wg0.conf:
==============
[Interface]
Address = 10.xxx.y.1/24, xxxx:xx:xxx:xxxx:yyyy:y::1/96
ListenPort = 1194
MTU = 1372
PrivateKey = (hidden)

[Peer]
PublicKey = (hidden)
PresharedKey = (hidden)
AllowedIPs = 10.xxx.y.z/32, xxxx:xx:xxx:xxxx:yyyy:y::z/128
==============

Is anyone else having the same problem?

Sincerely,
Ryuichiro