Steps to reproduce:

1. Create two hosts with web scenarios and tag source:host.
2. Add two web scenarios:
   1. with common tag.
   2. with unique tag.
3. Go to a dashboard and create a Web monitoring widget.
4. In the Scenario tags filter, set:
   1. source   equals   !@#$%^
5. Check widget rendering:
   1. Result: All web scenarios are displayed in the widget.
   2. Expected: Empty list should be displayed.
6. In the Scenario tags filter, set the unique tag.
7. Check widget rendering.
   1. Result: All web scenarios are displayed in the widget.
   2. Expected: Only one web scenario with the unique tag should be displayed.