Notification not going to specified channel

Hey there, I got the same problem. Here’s the content of my system data. The error log is empty.

# System
* **WordPress Version**: 4.8.12
* **Server Software**: Apache
* **PHP Version**: 7.0.31
* **MySQL Version**: 5.7.20
* **cURL Version**: 7.52.1

# Active Theme
* **Name**: Avada Child
* **Version**: 1.0.0
* **Theme URI**:

# Active Plugins
* **[Internal Link Juicer](https://internallinkjuicer.com)**: 1.1.5.2
* **[Ivory Search](https://ivorysearch.com)**: 4.2.1
* **[Akismet Anti-Spam](https://akismet.com/)**: 4.1.1
* **[Better Search Replace ](https://bettersearchreplace.com)**: 1.3.3
* **[Canonical Seo WordPress Plugin](http://www.shoutmeloud.com/)**: 2.1
* **[Capability Manager Enhanced](https://publishpress.com)**: 1.6.1
* **[Co-Authors Plus](http://wordpress.org/extend/plugins/co-authors-plus/)**: 3.4
* **[Contact Form 7](https://contactform7.com/)**: 4.9
* **[Cookie Notice](https://dfactory.eu/products/cookie-notice/)**: 1.2.46
* **[Crayon Syntax Highlighter](https://github.com/aramk/crayon-syntax-highlighter)**: 2.8.4
* **[Slack Notifications](https://www.dorzki.co.il)**: 2.0.7
* **[Easy Twitter Feed Widget](https://designorbital.com/easy-twitter-feed-widget/)**: 0.9
* **[EWWW Image Optimizer](https://wordpress.org/plugins/ewww-image-optimizer/)**: 4.2.1
* **[Fast Velocity Minify](http://fastvelocity.com)**: 2.6.0
* **[Featured Video Plus](http://yrnxt.com/wordpress/featured-video-plus/)**: 2.3.3
* **[Fusion Builder](http://www.theme-fusion.com)**: 1.2.2
* **[Fusion Core](http://theme-fusion.com)**: 3.2.2
* **[Jetpack von WordPress.com](https://jetpack.com)**: 5.4.1
* **[Mass delete unused tags](https://www.mijnpress.nl)**: 1.0.1
* **[MathJax-LaTeX]()**: 1.3.11
* **[Öffentliche Vorschau für Beiträge](https://dominikschilling.de/wp-plugins/public-post-preview/)**: 2.8.0
* **[Scripts n Styles](http://www.unfocus.com/projects/scripts-n-styles/)**: 3.5.1
* **[Shariff Wrapper](https://de.wordpress.org/plugins/shariff/)**: 4.3.0
* **[TablePress](https://tablepress.org/)**: 1.8.1
* **[Term Management Tools](http://scribu.net/wordpress/term-management-tools)**: 1.1.4
* **[TinyMCE Advanced](http://www.laptoptips.ca/projects/tinymce-advanced/)**: 5.0.1
* **[Yoast SEO](https://yoa.st/1uj)**: 7.5.1
* **[WP-Appbox](https://tchgdns.de/wp-appbox-app-badge-fuer-google-play-mac-app-store-windows-store-windows-phone-store-co/)**: 4.1.4
* **[WP Google My Business Auto Publish](https://www.northernbeacheswebsites.com.au)**: 2.17
* **[WP Mail SMTP](https://wpforms.com/)**: 1.3.3
* **[WP Super Cache](https://de.wordpress.org/plugins/wp-super-cache/)**: 1.6.4
* **[WP User Avatar](http://wordpress.org/plugins/wp-user-avatar/)**: 2.2.4

Maybe you need to add # in front of the channel names?