DNS Resolver leaks after reboot

[gschmidt]

Hi,

I have setup an OpenVPN client (ExpressVPN) in pfsense 2.4.2.
for DNS Leak Prevention I use the unbound DNS Resolver:
Selected Network Interface: LAN & Localhost
Selected Outgoing Network Interface: EXPRESSVPN

This setup is working (not leaking DNS)
However when I reboot the pfsense box my ISP IP address is leaked (dnsleaktest.com)
Until I restart the unbound DNS Resolver service in the Dashboard/Services tab.

Is this normal behaviour or is there a solution?