I had the same problem. I was using Bootstrap 4 along with a local style.css file.
Try removing float: left; for "#about h1, p" selector, and see if it works. I didn't set the "display: inline-block;" declaration for h1 and p elements and it still worked.
here is my code:
.about p {
  font-size: 25px;
  min-width: 300px;
  text-align: justify;
  text-indent: 15px;
  font-weight: bold;
}
.me {
  height: 400px;
  margin: 0 30px 10px 0;
  box-shadow: 2px 5px 10px 0 hsla(240, 100%, 35%, 1);
}
<head>
  <!-- link to Bootstrap CDN -->
  <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/css/bootstrap.min.css" integrity="sha384-MCw98/SFnGE8fJT3GXwEOngsV7Zt27NXFoaoApmYm81iuXoPkFOJwJ8ERdknLPMO" crossorigin="anonymous">
</head>
<body>
  <section class="container bg-primary text-white about" id="about">
        <img src="./images/me.JPG" alt="my picture" class="me rounded float-left"/>
        <h1 class="font-weight-bold display-4">About Me...</h1>
        <p>Hi there! My name is Mohsen, and I'm from Shiraz. I love to learn new things, and though I had just begun to learn about front-end web-development, I'm very
          passionate about it.</p>
      </section>
    </body>