Visits over time not showing (no replies)

I did a server/database migration of Piwik to a new domain following the instructions in FAQ.

I have the cron auto archiving set up and working.

Everything is ok apart from data is not showing in 'Visits Over Time' and 'Visits by Server Time' on some of the sites.

In all I am tracking about 20 sites, sometimes the selected the site will show both data and I if I reselect then they won't.