Different results in "Work detailed by resource" & "work detailed by activities"

Hi,

On a project where tickets are the driving concept, I have been careful that each ticket is linked to an  activity.
However, these two reports ("Work detailed by resource" & "work detailed by activities") show different results, although they should just be different view of the same work.

Some work seems to be excluded from "work detailed by activities".
In my example, it seems that time affected to (periodic) meetings is not included in this report, while it is in "Work detailed by resource".

Is this expected or a bug ?
If it is expected, why, or is there a workaround ?

Thanks,
Franck