Hello Priesh,
- For how long traffic pass through ASM on your system?
- Did you upgrade your system? Statistics can be deleted in case of upgrade.
- Did you check different time periods (last week, last month, last year, custom)? Sometimes you don't see statistics for e.g. last two weeks in case of custom period, but you can see it in case of last month period and vice versa - it depends on when exactly we start to gather statistics, this is how aggregation mechanism works.
In general, we should store all statistics from day one and we don't have any limitation for reporting, like we do have in case of Event Log. We should have ability to store all statistics for several years without any problem, until it will be manually deleted or until upgrade will be executed.
Thanks, Ivan