Smart Previews not downloading to Lightroom mobile

Hi

I've just updated lightroom classic to v11.5 and have lost the ability to see synced imaged in lightroom mobile. On both desktop and phone it can correctly tell me how many images in each collection, and I can see on my phone grey boxes representing the images, but the image previews never load. They just get stuck downloading. I've tried uninstalling and reinstalling lightroom mobile but no joy. I've had a look around the menus on classic to see if there's anything but no joy. Any help much appreciated

Thanks

Emma