Steps to reproduce:

1. Create a Web Scenario item
2. Create a trigger for web scenario item
3. Add TAGs on the Web Scenario Template and on the trigger template
4. Generate a problem event
5. The Event dont inherited tags from the template, only the trigger tags.
6. If you click on the trigger details on the event, they show the template tags

Result:

Event generated for web scenario item

Template trigger details

Problem was parttialy solved on ZBX-26259. 

Expected:
All tags from template, goes to event. We need this because we use this tags for oppening tickets in ServiceNow.