Reliably trigger alerts for Log Analytics log entries

The weird thing is that action group seems to be attached when I create alert via ARM. At least I can see it on Monitor -> Alerts -> "Manage alert rules" page (image 1 in attached screenshot). Action group is only missing when looking at alert rule via link from triggered alert instance ("Alert rule" in the "Essentials" section, image 2 in attached screenshot).

A tried to get alert action JSON using REST API - reference to action group it is there. After re-saving an alert from the Portal or by get/put REST API calls nothing changes in action JSON (except etag), but somehow such re-save fixes the issue, so something internal is definitely changed.

Here goes sample request I used to get alert action:

$actionUrl = "/subscriptions/{subscription id}/resourceGroups/{res group name}/providers/Microsoft.OperationalInsights/workspaces/cdm1drepomsf01/savedSearches/saved_search60eee2d2dc0b42dd87cd0a06b1c3f335/schedules/schedule_60eee2d2dc0b42dd87cd0a06b1c3f335/actions/action_60eee2d2dc0b42dd87cd0a06b1c3f335?api-version=2015-03-20"
$jsonStr = armclient get $actionUrl

And here is what I used to re-save alert action via REST API:

$json = $jsonStr | ConvertFrom-Json
$json2 = @{
  etag=$json.etag
  properties=$json.properties
}
$json2 = $json2 | ConvertTo-Json -Depth 3
$json2 | armclient put $actionUrl

API samples may be found here: https://docs.microsoft.com/en-us/azure/azure-monitor/platform/api-alerts.

You've mentioned that link points to an old API (it has "(Preview)" in title). Do you have a link to a new ARM API for Log Analytics alerts creation?