I'm sorry that you're having trouble with the Fixed Element Position feature in WordPress.
First, make sure that you're exporting using the most recent version of in5, version 3.8.11. You can check it by going to in5 > Info & Updates... and looking in the upper right of the in5 - Info & Updates dialog. If it's an older version, you can download the most recent version here:
If you're still having trouble after making sure that you're using the most recent version, we'd be happy to troubleshoot your files if you can send us the following:
- Your InDesign file (or a sample file that recreates the issue)
- Your html5_output folder
- The URL to your content on WordPress
You can send that content here: