Sorry for the delay in responding to this post!
I'm assuming you have considered this, but have you tried filtering your data to exclude the first thirty days?
Do you think you could include some screenshots describing what you are trying to accomplish in a bit more detail?
Also, which version of Yellowfin are you using? To check the build of Yellowfin you are using go to System Information under Administration > Admin Console > System Information. The version of Yellowfin is listed next to Application Version.
I look forward to hearing back!