When opening the dialog an existing filter condition on the grid is removed.
As far as I got in TAdvGridFilterDialog.FormShow when Grid is assigned there is a call to AddClear in which the two lines
Grid.Filter.Clear;
Grid.FilterActive := false;
remove an existing filter.
Is it possible to avoid this?
At this moment, it is by design that the dialog starts from an unfiltered situation.
In order to have this started from an existing or preset filter, extensions to the component will be needed.
A possible quick workaround could be to drop a new TAdvGridFilterPanel on a new form and open this as your own dialog.
I'll give it a try.