WordPress sometimes cuts or modfies our embed codes and therefore users cannot publish successful our widget.
Please follow the guide below as a work around solution.
1. Install the "Simple Code Embed" WP plugin. Click here
2. Activate the plugin
3. Create new post and find below the custom filed section.
4. Create a new field called CODE1 and paste the SVP embed code opposite the new custom field called CODE1
5. Within the actual article where the html editor is simply enter using capital letters %CODE1%
6. Save and Preview
See video tutorial