5.0 Beta 4 - root_url not working

I am working with 5.0 beta 4 and had this working in the latest stable of 4.6. My ini is below and you can see the different variations of root_urls that i have tried. As soon as i comment out the root_url and restart grafana works as normal on port 3000. Is this a bug or is there a config that i am missing?

protocol = http
http_addr =
http_port = 3000
domain = hostname.domain.com

;root_url = %(protocol)s://%(domain)s:3000/grafana
;root_url = %(protocol)s://%(domain)s:/grafana
;root_url = http://hostname.domain.com:3000/grafana

;enforce_domain = false
;router_logging = false
# the path relative working path
;static_root_path = public
;enable_gzip = false
;cert_file =
;cert_key =
;socket =

This can be closed. It was an nginx permissions issue on the proxy folder.