I am not sure but I had the same problem after added tables in HTML home design page. I added custom meta tags to index page to fix it and worked for me.
If you want to try adding meta tags open and edit index.php file. At the top of the file you will see:
<!doctype html><html lang="en"><head>
ADD inmediately below:
<!-- HTML Meta Tags -->
<title>Title of your app</title>
<meta name="description" content="your description">
<!-- Google / Search Engine Tags -->
<meta itemprop="name" content="Title">
<meta itemprop="description" content="Description">
<meta itemprop="image" content="URL image">
<!-- Facebook Meta Tags -->
<meta property="og:url" content="your URL site">
<meta property="og:type" content="website">
<meta property="og:title" content="Title">
<meta property="og:description" content="descrption">
<meta property="og:image" content="image URL">
<!-- Twitter Meta Tags -->
<meta name="twitter:card" content="summary_large_image">
<meta name="twitter:title" content="Title">
<meta name="twitter:description" content="Description">
<meta name="twitter:image" content="Image URL">
<!-- End Meta Tags -->
Save your file and that's all!