Steps to reproduce:

1. Create template
2. Add web check to template with URL that will fail (timeout, FW, host doesn't exist etc.), for example https://some-rand-non-existing-domain-asdf.com
3. On same template add trigger that is linked with some step-based key (e.g. web.test.time[<SCENARIO>,<STEP>,resp]), function doesn't matter
4. Add template to host, wait for web check to happen. Latest data page should show data for:
   • Download speed for scenario
   • Failed step of scenario
   • Last error message of scenario
     And items without data:
   • Download speed for step
   • Response code for step
   • Response time for step
     In latest data you should see that scenario based items are populated, but step based items are empty
5. Use API to update any property for web scenario, for example, URL

{
  "jsonrpc": "2.0",
  "method": "httptest.update",
  "params": {
    "httptestid": "1",
    "delay": "2m",
    "steps": [
      {
        "name": "test",
        "url": "https://some-rand-non-existing-domain-asdf-update.com",
        "follow_redirects": 1,
        "no": 1
      }
    ]
  },
  "auth": "****",
  "id": 1
} 

Result:

Web scenario is updated, but trigger that was linked to it is deleted. Step related metrics that previously showed empty in latest data are now completely gone.

Expected:
Web scenario is updated, trigger is not changed

I should also note that now it's not possible to add new web scenario based triggers to template in both UI and API. If trying to add something like "last(/testtemplate1/web.test.rspcode[<SCENARIO>,<STEP>])=0" Zabbix throws error about key missing from host (not template).