Some of my PHP string disappears when being passed into SQL - php

Question

I've created a Wordpress plugin that detects when a post is published and creates a topic in a phpBB installation.
As part of the plugin, the Wordpress post's excerpt is passed to the phpBB SQL database as the post text, followed by a few line breaks and a 'read more' link that is a permalink to the Wordpress post.
The excerpt + link is created as follows:
$wparticle_excerpt = get_the_excerpt()."<br /><br />Click here to read the full article →";
Then it's escaped:
$wparticle_excerpt = $con->real_escape_string( $wparticle_excerpt );
And is then written into the SQL database using the following query:
$sql_write_post = "INSERT INTO phpbb_posts (
topic_id,
forum_id,
poster_id,
icon_id,
post_time,
post_approved,
post_reported,
enable_bbcode,
enable_smilies,
enable_magic_url,
enable_sig,
post_subject,
post_text,
post_checksum,
post_attachment,
post_postcount,
post_edit_time,
post_edit_user,
post_edit_count,
post_edit_locked
) VALUES (
/* topic_id */ $new_topic_id,
/* forum_id */ $forum_to_post_in,
/* poster_id */ $userid_to_assign,
/* icon_id */ 0,
/* post_time */ $date_to_assign,
/* post_approved */ 1,
/* post_reported */ 0,
/* enable_bbcode */ 0,
/* enable_smilies */ 0,
/* enable_magic_url */ 1,
/* enable_sig */ 0,
/* post_subject */ '$wparticle_title',
/* post_text */ '$wparticle_excerpt',
/* post_checksum */ '$wparticle_excerpt_md5',
/* post_attachment */ 0,
/* post_postcount */ 1,
/* post_edit_time */ 0,
/* post_edit_user */ 0,
/* post_edit_count */ 0,
/* post_edit_locked */ 0
)";
if (!mysqli_query($con,$sql_write_post)) { die ("Error while creating post: " . mysqli_error($con)); }
The problem is that when I check the output, all I get are the two line breaks and the read more link. The actual excerpt, the part created by get_the_excerpt(), is completely gone. All I get is this:
<br />
<br />
Click here to read the full article →
I've dumped the $wparticle_excerpt variable after escaping it, and I know it's good. It's just one long string.
If I put any text in front of the excerpt, that stays, as long as it's hard-coded in PHP. Then there's a blank space where the excerpt should be, then the line breaks. No matter what I do I can't keep the excerpt there, it just disappears somewhere.
I'm sure this is the most simple thing but I'm mostly self-taught and I have no idea how or why this is happening. Any help would be incredibly appreciated. Please let me know if I haven't explained something properly.
The phpbb_posts table I'm writing to is utf8_bin and the post_text field in there is mediumtext type and utf8_bin, if this is of any help.