Missing highlights, notes and tags

Hi There, I have been marking scriptures with my young son on his ipad for about a month now. When I created an LDS account for him, and signed in with it on the ipad to save everything, everything was gone. All his highlights, tags and notes/notebooks. There is nothing there, and it is not syncing on the PC either.
Can anyone shed some light on this please. He has put in a lot of work starting to mark his scriptures as we have been learning.
Thanks Kath

Just a bit more of extra information. I now cannot highlight anything in the scriptures since signing in with his LDS account.