Hi Becky,
The blue line is the ideal (required) burndown rate, not the actual burndown rate. The red line is the actual burndown rate.
However, if you think the burndown chart data is not correct/up-to-date, then you can click (top-right) on 'Iteration Actions' then 'Synchronize Burndown Data'. Then reload your Storyboard and see if the data looks correct. Curious to know how you go, so please let us know!
Regards, David
p.s. In case you haven't yet had a look, there's good documentation at
https://support.workfront.com/hc/en-us/articles/218008458-Using-the-Agile-Burndown-Chart