getWithPopup hangs up

Questions OAuth/OIDC
1

I’m using @okta/okta-auth-js client for signing in to my website with Okta users.

            const authOktaClient = new OktaAuth({
                issuer: oktaData.issuer,  
                clientId: oktaData.clientId,
                redirectUri: beUrl + '/okta/callback`,
                responseType: 'code',
                pkce: false
            });

            authOktaClient.token.getWithPopup({
                prompt: 'login'
            }).then(res => {
                let tokens = res.tokens;
                authOktaClient.tokenManager.setTokens(tokens);
                cb(null, tokens);
            }, err => {
                cb(err);
            });

At the beginning I received an authorization code request form Okta to my BE and successfully converted it to the Okta access_token. For all sequential calls I see an Okta popup with hardcoded username that cannot be changed and when I enter a password the Okta completely bypasses my BE, redirects to the blank page and hangs up there:
https://mydomain.okta.com/login/step-up/redirect?stateToken=00g4GtzI98_asoZlkxIFg89xwOKO2fBsO7PvL_SpIw

Cleaning browser cache doesn’t help.

2

P.S. On the other hand the authOktaClient.token.getWithRedirect flow reaches the BE and after that completes well.

3

What is BE? Is that an external identity provider?

4

BE - this is our BackEnd server with express.js
When I’m using Code Authorization or Implicit flows the Okta request doesn’t reach it at all but redirect to the page https://mydomain.okta.com/login/step-up/redirect that has some window.postMessage commands. It looks like the communication between the main SDK script and the opened popups doesn’t work.