OpenVPN cannot reach other clients, arp replies go to client instead of server

I have OpenVPN configured on three VirtualBox VMs running Ubuntu 16.04.

The network configuration is as follows:
network config picture.

Server config:

local 192.168.2.2
port 1194
proto udp
dev tap0

ca ca.crt
cert server.crt
key server.key
dh dh2048.pem

ifconfig-pool-persist ipp.txt

server-bridge 192.168.0.2 255.255.255.0 192.168.0.50 192.168.0.100
client-to-client

keepalive 10 20
cipher AES-128-CBC
comp-lzo

persist-key
persist-tun
verb 3

Client config:

client
dev tap
proto udp

remote 192.168.2.2 1194
resolv-retry infinite

nobind
persist-key
persist-tun

ca ca.crt
cert client1.crt
key client1.key

cipher AES-128-CBC
comp-lzo
verb 3

I am using the bridge-start and bridge-stop scripts that come with OpenVPN to use the bridge. Connection opens without no problems. I can ping the clients from the server and the server from the clients. The problem is that I cannot ping client-to-client, e.g. ping from the remote client (lab3) to the other client (lab2) just gets From 192.168.0.50 icmp_seq=1 Destination Host Unreachable.

Seems that the problem has something to do with ARP, because when I tcpdump on br0 on the server, I see that there is a question
ARP, Request who-has 192.168.0.1 tell 192.168.0.50, length 28.
Then on the client (lab2) I see:

ARP, Request who-has 192.168.0.1 tell 192.168.0.50, length 46
ARP, Reply 192.168.0.1 is-at 08:00:27:c8:1c:c7, length 28

But the replies don't seem to reach any machine.

When the OpenVPN connection is open, the routing table seems to be correct:

Server:

default via 10.0.2.1 dev enp0s3 
10.0.2.0/24 dev enp0s3  proto kernel  scope link  src 10.0.2.4 
192.168.0.0/24 dev br0  proto kernel  scope link  src 192.168.0.2 
192.168.2.0/24 dev enp0s9  scope link 
192.168.2.0/24 dev enp0s9  proto kernel  scope link  src 192.168.2.2

Client:

default via 10.0.2.1 dev enp0s3 
10.0.2.0/24 dev enp0s3  proto kernel  scope link  src 10.0.2.7 
192.168.0.0/24 dev enp0s8  proto kernel  scope link  src 192.168.0.1 

Remote Client:

default via 10.0.2.1 dev enp0s3 
10.0.2.0/24 dev enp0s3  proto kernel  scope link  src 10.0.2.6 
192.168.0.0/24 dev tap0  proto kernel  scope link  src 192.168.0.50 
192.168.2.0/24 dev enp0s8  proto kernel  scope link  src 192.168.2.1 

Any ideas how to get the messages to flow between the two clients? Am I doing something wrong or missing something in the configurations?