authStateManager is undefined in Vue application

I’m attempting to set up Okta authentication in my Vue application and receiving an error upon app startup with the following stack trace:

vue.esm.js:3767 TypeError: Cannot read properties of undefined (reading 'getAuthState')
    at (okta-vue.ts:43:45)
    at Vue.mergedInstanceDataFn (vue.esm.js:5252:29)
    at getData (vue.esm.js:4417:21)
    at initData (vue.esm.js:4381:42)
    at initState (vue.esm.js:4322:9)
    at Vue2._init (vue.esm.js:4711:9)
    at new Vue (vue.esm.js:5772:10)
    at new Store2 (vuex.esm.js:397:21)
    at createDirectStore (direct-vuex.esm.js:4:22)
    at index.ts:67:5

It appears oktaAuth.authStateManager is undefined. There are additional errors as well, occurring any time the code tries to access a property on authStateManager (such as when subscribing, e.g., oktaAuth.authStateManager.subscribe(…)).

I am using the following package versions:

    "@okta/okta-vue": "3.1.0",
    "@okta/okta-auth-js": "4.1.2",
    "vue": "~2.7.14",
    "vue-router": "^3.6.5",

Here is my code:

router index.ts:

const oktaAuth = new OktaAuth({
  issuer: 'https://<my okta dev domain>.com/oauth2/default',
  clientId: <my client id>,
  redirectUri: window.location.origin + '/login/callback',
  scopes: ['openid', 'profile', 'email']

Vue.use(OktaVue, { oktaAuth })

I am not sure if this is relevant, but when OktaAuth is initialized, the OktaAuthNode constructor is called, which does not appear to call the AuthStateManager constructor. However, in the okta-auth-js code I can see that OktaAuthBrowser does call the AuthStateManager constructor. Is it possible the code is calling the incorrect constructor? If not, what else might the issue be?