Equation is moved to the extreme right after upgrading to MathJax v3

I’ve a personal blog built on minimal-mistakes Jekyll theme. Some of the posts use LaTex parsed by MathJax. I’ve been using MathJax v2 with the following configuration:

MathJax.Hub.Config({

  showProcessingMessages: false,
     messageStyle: "none",
     tex2jax: {
       inlineMath: [ ['$','$'], ["\(","\)"] ],
       displayMath: [ ['$$','$$'], ["\[","\]"] ],
       processEscapes: true
     },
     TeX: {
       MultLineWidth: "100%",
       equationNumbers: { autoNumber: "AMS" }
     },
     "HTML-CSS": { fonts: ["Latin-Modern"] }

});

MathJax.js?config=TeX-AMS-MML_HTMLorMML

Here’s an equation and its output.

$$
E[X] = sum_{i=1}^{k-1}sum_{j=i+1}^{k} X_{ij}Pr[text{i and j have the same birthday}]
$$
$$ Pr[text{i and j have unique birthdays}] = 365/365 * 364/365 $$ ($$ i $$ may have been born on any of the $$ 365 $$ days, and $$ j $$ on any of the remaining $$ 364 $$ days).
$$
therefore Pr[text{i and j have the same birthday}] = 1 - frac{364}{365} = frac{1}{365} \
begin{equation*}
begin{aligned}
  E[X] & = frac{1}{365} * sum_{i=1}^{k-1}sum_{j=i+1}^{k} X_{ij} \
   & = frac{1}{365} * sum_{i=1}^{k-1} (k - i - 1 + 1) \
   & = frac{1}{365} * sum_{i=1}^{k-1} (k - i) \
   & = frac{1}{365} * (sum_{i=1}^{k-1} k - mathop{sum_{i=1}^{k-1}} i) \
   & = frac{1}{365} * (k(k - 1) - (1 + 2 +...+ k - 1)) \
   & = frac{1}{365} * (k(k - 1) - frac{k(k - 1)}{2}) \
   & = frac{k(k - 1)}{(365 * 2)}
end{aligned}
end{equation*}
$$

I upgraded MaxJax to v3, and obtained the v3 configuration using the conversion tool provided by MathJax.

v3 configuration:

window.MathJax = {
  tex: {
    inlineMath: [ ['$','$'], ["\(","\)"] ],
    displayMath: [ ['$$','$$'], ["\[","\]"] ],
    processEscapes: true,
    multlineWidth: "100%",
    tags: "ams"
  },
  options: {
    ignoreHtmlClass: 'tex2jax_ignore',
    processHtmlClass: 'tex2jax_process'
  }
};

As you can see, the equation is moved to the extreme right, and overlaid on top of the text above it. How do I fix this?