Point Subdomain in Google Domains to Google Compute Instance running WordPress

I have installed wordpress (the bitnami multi-site version) to a compute instance from the marketplace. I’ve also recently moved my domain registration to domains.google.com. Everything is working fine with the top-level domain. I also set up a subdomain, wp.mydomain.com in the domains interface pointed to the static external IP I configured for the compute instance running wordpress. When I go to wp.mydomain.com it redirects me to http://.xip.io/.

How do I get this set up so that I stay on wp.mydomain.com instead of going to my ip address as the url?