Don’t worry, if you see that your reputation is suddenly dropped when you believe sending activity remained same for all month or week and no big changes were made.
It seems Google has fixed issues related to their Postmaster platform which is now a relief for most of the senders. All statistics are visible now, even for missing dates which were not showing earlier.
There is an ongoing issue with statistics/graphs in Google Postmaster (https://postmaster.google.com). But don’t get nervous if your account is not displaying updated statistics post June 13, 2019.