I have similar problem with my 50PUS8204/12 although it got worse and it doesnt play the app anymore. I have fire stick which gets around the problem but it is not ideal. I also found out that my model is not certified by BBC iplayer and you can check yours on https://www.bbc.co.uk/iplayer/help/questions/supported-devices/philips
Really disaapointed with Philips