Apple News app stories not loading linked Twitter and Facebook content

Approximately a week ago, while reading stories from Apple News on my iPad (Air 2, running iOS 12.0.1), I noticed that where a story included linked Twitter tweets or Facebook posts, those tweets and posts did not appear. Instead, they were replaced by a spinning activity indicator. The indicator did not go away, and the linked content never appeared. I checked whether the same thing was happening on my iPhone (iPhone 6, running iOS 12.0.1) and my MacBook (Retina 13in, late 2015, running OS 10.14). The iPhone produced the same response, but the MacBook brought the linked content up with only a short wait.

At this point, all devices were connected to my home wifi, so I was curious to see if the problem was somehow related to the wifi connection. I switched wifi on the iPhone and iPad off, and hot spotted the iPad to the iPhone. Miraculously, the spinning activity indicator was replaced with the missing content on both devices. Meanwhile, the MacBook remained on the wifi, as it was happily displaying the linked content. I wondered whether the distance between the wifi router (Airport Extreme, running version 7.7.9 software) and the devices was an issue. Irrespective of where I was in the house - sitting right on top of the router and getting 96Mbps, or out in the garden (30 metres away, through multiple internal walls and at least two brick walls) with a miserly 12.3Mbps - I got the same endlessly spinning activity indicator when the iPhone and iPad were connected to the wifi.

I should add that, up until about a week ago, both iPhone and iPad would happily display linked facebook and Twitter content within News stories while the devices were on the wifi. As far as I'm aware, nothing has changed in the configuration of the Airport Extreme.

Anyone got any ideas about what's going on?