I decreased the rent a bit and the list disappeared, even though the map shows matches. When I reload the page the list shows for a split second before disappea

I decreased the rent a bit and the list disappeared, even though the map shows matches. When I reload the page the list shows for a split second before disappearing. (Chrome on OS X, this is the link: http://www.openrent.co.uk/properties-to-rent/london-united-kingdom?term=London,%20United%20Kingdom&lngn=-0.127683100000013&latn=51.5073346&within=60&&prices_min=250&prices_max=680 http://www.openrent.co.uk/properties-to-rent/london-united-k... ). What's the difference between the gray and blue markers on the map?