iCloud Photo Library not updated in two weeks

My iPhone 6 Plus has not been updating my iCloud Photo Library in two weeks. I got a message last week to say a week had gone by without being able to upload to the Photo Library and told me to connect to WiFi to resume. My phone is always connected to WiFi in the house. and the yesterday the message appeared again but saying 2 weeks had now gone by without an update.

I went into the settings and it just says 'Uploading 272 photos' but it never changes. I've rebooted my phone, tried turning photo library off and on but nothing works. Can anyone advise?