Can't compile Angular 10 with Elastic APM Angular package

I created new, blank angular app
I installed the Elastic APM Angular package (https://www.elastic.co/guide/en/apm/agent/rum-js/current/angular-integration.html)
The instructions are nice and seem simple but they are not complete.
I get a console message:

apm-service.js:8 Uncaught TypeError: Reflect.metadata is not a function
at Module.6SBv (apm-service.js:8)

I googled around and found this issue: Has anyone been able to use @elastic/apm-rum-angular with aot?
It suggested adding either import 'reflect-metadata'; or import 'core-js/es/reflect'; in polyfils.js It does not help.

I am able to use base agent-rum-js without angular extensions.

APM Agent language and version:
@elastic/apm-rum-angular 1.1.8,
@elastic/apm-rum-core 5.7.0,
@elastic/apm-rum 5.6.1,

Browser version:
Chrome 85

Original install method (e.g. download page, yum, deb, from source, etc.) and version:
npm install @elastic/apm-rum-angular --save

Fresh install or upgraded from other version?
fresh install on blank new app

Steps to reproduce:

  1. follow official doc https://www.elastic.co/guide/en/apm/agent/rum-js/current/angular-integration.html#installing-angular-integration
  2. it doesn't compile

Errors in browser console (if relevant):

apm-service.js:8 Uncaught TypeError: Reflect.metadata is not a function
at Module.6SBv (apm-service.js:8)
at webpack_require (bootstrap:79)
at Module.+/6d (index.js:1)
at webpack_require (bootstrap:79)
at Module.ZAI4 (app.module.ts:1)
at webpack_require (bootstrap:79)
at Module.zUnb (main.ts:1)
at webpack_require (bootstrap:79)
at Object.0 (main.js:11)
at webpack_require (bootstrap:79)