Android Mobile Stuck on Storing Album Locally

For the last week I'm unable to get Android Mobile to sync any albums locallly on the device.

It always syncs to a reasonably high number of photos but it just never stops syncing. I've left the device on with the screen on overnight but it still won't sync.

I've cleared the storage and cache on the device, and even reintsalled a few times and tried again. I've also tried syncing different albums with the result is always the same. 

The device is set to store only smart previews (IE the default setting.

Lightroom classsic and lightroom for PC both are syncing perfectly.

The cat