Wireless long-term graph bug?

Hello,
I was looking at my SSID graphs from my Cisco 9800 controller and noticed what appears to be a bug with long-term graphs.

the short term graphs show max clients of over 900 (this is 6hr graph):
image

2 week graph:
image

2 month graph:
image

but 1year and 2year show (426 max):
image

Thanks,
Aaron