Amplify Matrix with missing data

I just did setup the Amplify dashboard on my server.

I see a no data between times for below two matrix, is it reflecting some kind of issue with server or is it OK (i had enabled page-speed for few days and now its disabled, i have lot of 404 for page-speed)

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Also, there is no data shown for Disk Buffered and Upstream Error (do i need to add something for the same in log)

Anybody enlightening me on the same could be a great.

Thanks

 

the server was lightly used at that time and matrix data was from hour (also i am not using live statistic).

when i checked dashboard with 1 day data, there are no breaks shown in it but when i go to hour, those 2 graphs comes with no data patches in between times.
below is days statistic.