Clips not posting to Facebook from iPad

I used to be able to post video clips from both my phone and iPad but recently anything I try to post to Facebook from my iPad (iPad Pro) stalls at ‘connection is taking too long to upload’ so I click on ‘send when connected’ and there it sits ‘preparing video’. Yesterday it sat all day doing that because I forgot about it. When that happens, I have to delete the app and reinstall it to get any other screen. From the iPhone there’s no problem. Sharing (save) to OneDrive is also fine. All devices are up to date. It doesn’t matter where in the house the iPad is or if it’s plugged into the socket next to one of the wifi boosters. And anyway, connection was never an issue until recently and only with Facebook. Ideas welcome.