IOS not syncing with Dropbox

Operating system

iOS

Joplin version

13.0.7

Desktop version info

13.0.15

Sync target

Dropbox

What issue do you have?

The IOS version does not sync anything at all. I have Joplin on a laptop and desktop - those sync OK. All the Joplin data appears to be in Dropbox on the IOS version - it's just ignored.