App Alert show does not work

Hi all,

I added a new file custom/clients/base/views/merge-duplicates/merge-duplicates.js to my code to extend the Merge Duplicate Process with some logic. My logic is running fine, but I also want to display an Alert message for the user before my logic is executed.

However, it is not shown until the merge is finished.

//  custom/clients/base/views/merge-duplicates/merge-duplicates.js :
({
    extendsFrom: 'MergeDuplicatesView',
    
    _savePrimary: function () {
        app.alert.show('my_alert', {
            level: 'info',
            messages: 'Please wait ...'
        });

        // ... execute some logic ...

        this._super('_savePrimary');
        app.alert.dismiss('my_alert');
    },
    
    ...
})

I also tried to place the app.alert.show inside the triggerSave() function or other functions. 

But after merge_confirmation (Standard Code below) is shown in the GUI and confirmed - no other app.alert.show works:

// clients/base/views/merge-duplicates/merge-duplicates.js:

    triggerSave: function() {
        var self = this,
            alternativeModels = _.without(this.collection.models, this.primaryRecord),
            alternativeModelNames = [];

        _.each(alternativeModels, function(model) {
            alternativeModelNames.push(app.utils.getRecordName(model));
        }, this);

        this.clearValidationErrors(this.getFieldNames());
        app.alert.show('merge_confirmation', {
            level: 'confirmation',
            messages: app.lang.get('LBL_MERGE_DUPLICATES_CONFIRM') + ' ' +
                // FIXME needs to be removed on SC-4494.
                Handlebars.Utils.escapeExpression(alternativeModelNames.join(', ')) + '. ' +
                app.lang.get('LBL_MERGE_DUPLICATES_PROCEED'),
            onConfirm: _.bind(this._savePrimary, this)
        });
    },

If i place app.alert into the _delegateEvents() function. My alert is shown, but already before the Save Button is clicked.

Can you help me on this?