Items not respecting Update Interval?

[Moebius]

On a Zabbix 6.4.11 server with 6.4.x Linux and Windows agents, I just realized that many items with a given update interval are not respecting it. The following are several examples from the Latest Data of similar items, with different update intervals, with the Last Check column that clearly shows the problem.
Looking at the latest values, it seems that these items are checked exactly once every 24 hours (with the some exceptions: in the last screenshot the Number of Installed Packages is checked exactly once every 12 hours).
Many other items, not shown here, respect their update intervals.
All items come from the standard Windows and Linux templates. Some hosts use Agent while others use Agent2; all passive agents.

I have been unable to understand why some items (and not others) are checked once or twice a day, irrelevant of their Update Interval. What am I missing here? Is it a bug or some documentation note that I inadvertently skipped??












I am not able to figure this out. Please help!!!

[cyber]

Not really sure, as there is probably a missing pic here... but maybe there is some "discard with heartbeat" preprocessing involved..?

[cyber]

Not really sure, as there is probably a missing pic here... but maybe there is some "discard with heartbeat" preprocessing involved..?

[Moebius]

Hello Cyber. Spot on! I didn't even know of this feature. It was exactly that: some items with "discard with heartbeat = 1d", other items with 12h. Thank you so much.

The items come from standard Linux and Windows template. Since the meaning of the "discard" preprocessing is - as I get it - to avoid spamming the Zabbix server with useless values when the checks are made with high frequency, I don't really understand why this preprocessing has been put in place with update intervals of 1m or even more.

Also, I had attached 3 pics to my first post which have disappeared, don't know why.
I am reattaching one of them as an example.

[cyber]

Discard with heartbeat is for values that do not change too often, but when it changes, you want to know about it quickly... Then use use short check time but discard values with a heartbeat of 1d or something, just keeping one value per day, if nothing changes. It will of course save all the changes, so you can have trigger based on change for example.