xml dailysummary empty for pws but exists in json

xml dailysummary empty for pws but exists in json

Compare:
http://api.wunderground.com/api/[KEY]/history_20150214/q/pws:IGLASGOW1.xml<br>with<br>http://api.wunderground.com/api/[KEY]/history_20150214/q/pws:IGLASGOW1.json

The dailysummary element in the xml has 21 summary children all with only date elements all of which are empty. The json version has a single - well-formed looking and populated dailysummary element.
I've tested this with a number of airport stations and a number of pws stations - as far as I can tell the airport locations are all fine - the xml has the 'correct' data and all the pws locations have 'bad' dailysummary data.

Any ideas?