The console abruptly closes when starting and errors can be seen in /var/log/libvirt/qemu/<vm>.log:
((null):4782): Spice-Warning **: reds.c:2819:reds_handle_ssl_accept: SSL_accept failed, error=1

and on the local client in /var/log/messages:
spice: (remote-viewer:4383): GSpice-WARNING *: loading ca certs from /var/tmp/trustore.pem-BDU5AX failed
Spice-Warning *: ssl_verify.c:428:openssl_verify: Error in certificate chain verification: self signed certificate in certificate chain

This is because the certificate is not being returned by the cacert method in app/models/compute_resources/foreman/model/ovirt.rb