Difficulty in mocking an async function from external library

[vaibhav6496]

I've a function used in my Angular app from a library: '@sec/blindfold'. The function name is encryptStr. It's an async function with signature as below:
async function encryptStr(data: EncryptInput): Promise<StringResult> where StringResult is an interface below:

export interface StringResult {
	result: string | null;
        error: Error | null;
}

The encryptStr calls bunch of external APIs, so instead of intercepting those calls I tried to stub the encryptStr in my cypress tests like below:

import * as blindFoldUtils from '@sec/blindfold';
describe('Certificates functionality', () => {
	let initCertValue, initKeyValue;
	const encryptKeyValue = 'somesecretValuefortesting';
	beforeEach(() => {
            cy.stub(blindFoldUtils, 'encryptStr').resolves({ result: encryptKeyValue, error: null });
     });
});

However, I can still see the original encryptStr is being called as the network tab shows call to the external APIs. Am I missing something? How to stub such an external async function's response in cypress?