Timestamp varbind does not show a value in Events. The data type is timeticks.
Per the documentation:
There are multiple options for converting varbind values for date and time. But the data type of timeticks is not specified.
The K option successfully mapped the timeticks data type values.
So, in the CsEvFormat file if the varbind is data type timeticks and for example is varbind 1 it will appear as follows:
If this value in the CsEvFormat file is updated, please go to the OneClick Web Page -> Administration -> Update Alarm and Event Files -> Update
That way the change will take effect.