Lightroom Mobile on iPad not syncing with Lightroom Classic on desktop (Mac)

Hello,

I have been using Lightroom Mobile on my iPad to edit my photos on the go for a number of years now without any problems.  When I would open Lightroom Classic on my desktop all my edits would sync seemlessly. Since December 2021 when I updated to the latest version of LRC I have had all sorts of problems with syncing between the devices. Sometimes most of the images will sync but then around 10-20% of the collection won't and I can't tell immediately which ones are synced and which haven't.  The number of images when sorting by ratings don't match up.  I have tried 'delete all synced data' a number of times now and even deleted the 'Sync.lrdata' file and have rebuilt the synced data a few times but I'm still having problems. I have reinstalled both Lightroom Classic (version 11.1) on desktop and Lightroom Mobile (version 7.1.1) on iPad and updated the OS on both (MAC OS Monerey version 12.1 / iPad 15.2.1.)

I have just tried syncing a new collection and nothing has synced at all although I have a green tick 'Synced' in LRC and 'synced and backed up on ipad.'

Please help! This has been an essential part of my workflow for years and is now unusable.

Many thanks