Ok I figured it out.
When I checked the HUE server logs I found:
WebHdfsException: SecurityException: Failed to obtain user group information: org.apache.hadoop.security.authorize.AuthorizationException: User: hue is not allowed to impersonate hdfs (error 401)
When I looked at my core-site.xml file for HDFS I found that I had put Hue (and not lowercase hue) for the following values:
for proxy user permission. Check your case sensitivity people! arg :(*