Thanks ObiWan and MrNobody, I am aware of the option of maunally deleting assets, and I am also aware of the 30 days not seen requirement for automated cleaning. The fields you see in the provided screenshot are exclusively coming for the tblAssets table, and you can see tblAsset.Lastseen = 10-10-2014. That does not match with the 30 days parameter.... However... many assets are not having a "lastIPscan" date, as they were never discovered during an IP scan. That is also clear in the screenshot I provided. This is typical for travelling employees and consultants who only now and then are visible in the network, as they are typically at work in the offices of our clients. When they are in our office they do not make money, so preferable we see them as little as possible. In the settings I limited the "set to not active" to 60 days not seen and the "delete" to 365 days not seen.
I am not aware when in the process of daily life the value for LastActiveScan is filled-in. Many assets do have only blanks there. But I also see many units with a date Lastseen in 2015 and a date LastActiveScan in 2012 (see the bottom of the screenshot) and a blank LastIPscan. In my view these should have been automatically removed?
Probably it's best if I log a support-case.
Thank you for thinking with me!