It sounds like you are experiencing a common issue with the display of your header template in the frontend while using Elementor and the Porto theme. Here are some steps you can take to troubleshoot and potentially resolve the problem:
Clear your browser cache and any caching plugins you might have installed on your WordPress site. Sometimes, changes may not reflect in the front end due to cached data.
Theme and Elementor Updates:
Ensure that both your Porto theme and Elementor plugin are up to date. Sometimes, compatibility issues arise with outdated themes or plugins. if the theme and its necessary plugins are outdated then you can update them by following this article: https://www.portotheme.com/wordpress/porto/documentation/update-theme/
We hope this information helps.