If the issue persists then I would like to ask you to follow this steps in order to isolate the cause of the issue:
- Back up your site first before making any change, this is for security reasons.
- Update all outdated plugins and themes.
- Flush any cache memory that might exists.
- Go to WPML -> Support -> Troubleshooting link -> Apply the steps pointed out in the attached image.
- Deactivate all the plugins that are not related to WPML.
- Switch for a moment to a WordPress default theme like Twenty Seventeen.
- If the issue is gone, activate one by one to see with which one there is an interaction issue.
Could you tell me the result of this steps?