Steps needed to run in ie 11

add polyfills for ie

import "core-js/stable";
import "regenerator-runtime/runtime";

add polyfills for webcomponents

import "@webcomponents/webcomponentsjs"

and set the browserlist in a browserlist file or package.json

[
    ">0.2%",
    "not dead",
    "not op_mini all",
    "IE 11"
  ]

and set up babelrc to transpile

{
    "plugins": [
        "@babel/plugin-transform-classes"
    ],
    "presets": ["@babel/preset-env"]
}

Why This isn't working.

right now this will not work, because lit-element uses the extends keyword and const which is not valid in IE, and with parcel bundler node_modules are not transpiled. It does mention being able to transpile aliased modules but I have gotten around to testing it, and it is not well documented.