OPNsense 19.1.5_1: after ugrade/update from 19.1.1 no radvd and dhcpd6

[Drohne]

After upgrading OPNsense 19.1.1 to 19.1.5_1 today (2019-04-09) the service radvd and dhcpd6 are rejecting to start. I can see an empty /var/etc/radvd.conf file, which is strange, since we have had already configured that service and running. When entering the web-gui for configuration of Router Advertisement beneath Services, configuring works fine and it seems persistent, but  trying to start the service via clicking on the start symbol fails.

radvd is configured "Router only" and we use NPTv6 (uplink is dial-in via pppoe).
DHCPv6 is also not willing to start anymore.

Thanks in advance for helping