Dart Group data out of date

Shares in Dart Group PLC (DTG) do not seem to be showing the current price. They’ve gone up 15% or so this morning but the chart in my desktop view seems to be showing the price from yesterday afternoon so I can’t sell my shares.

(Just managed to sell via a Limit order so no loss but if I hadn’t been monitoring this elsewhere I might have missed out on this.)

Chart is up to date on my web app - current buy price 661

Is on my desktop now as well but was definitely well behind the market - I’d spotted this on a site that is 15 minutes behind live pricing.