dnsmasq is NOT supposed to run.
The reason Admin page shows lost connection to api is because FTLDNS failed to start (because dnsmasq is occupying port 53).
In the Beta version (and future stable releases) dnsmasq is no longer needed.
What you can do is stop dnsmasq manually with sudo systemctl stop dnsmasq.
then you need to restart FTLDNS with sudo systemct start pihole-FTL.service
that should bring FTLDNS up and everything should work.
You can also uninstall dnsmasq if it's something you don't need (should be OK to remove).
Are you running custom entries in this file ?