Table ActionHandler weird behaviour

I have a Problem with a ActionHandler on a Table with a ContainerDataSource (BeanItemContainer).

I want to check a property in the selected Item, as I implemented like this:

resultTable.addActionHandler(new Action.Handler() {
    @Override
    public Action[] getActions(Object target, Object sender) {
       
        if( sender instanceof TypedTable ) {

            TypedTable<Kontotransaktion> source = (TypedTable<Kontotransaktion>) sender;

            if( source.getValue() != null ) {
                if( ((BeanItem<Kontotransaktion>) source.getContainerDataSource().getItem(source.getValue())).getBean() instanceof Kontotransaktion ) {
                    Kontotransaktion currentTransaction = ((BeanItem<Kontotransaktion>) source.getContainerDataSource().getItem(source.getValue())).getBean();
                    if(currentTransaction.getBuchungsReferenz() != null) {
                        //Booking referenced
                        return new Action[] {zeigeBuchung};
                    } else {
                        //No booking referenced
                        return new Action[] {verknuepfen, neueBuchung};
                    }
                }
            }
        }
    return null;
}

When I now right-click a Item in the Table, nothing happens. (Not even the ActionHandler#getActions() method gets called)

But if you select a Item by left-clicking it and right-clicking somewhere in the whitespace in the table - you can actually see the correct Action Items.

So basically the problem is that as it seems the actionhandler doesn't get triggered by right clicking a Item in a ContainerDataSource in the table.

Any similar cases known?
Any suggestions are appreciated!