Hello,
Sorry to say but it seems to be an issue related to third party Plugin on your Site.
Could you please once take complete Backup of your Site first, then try deactivating all the third party Plugins on your Site (including the WPML ones too), remaining the Theme required ones activated. If the issue gets resolved, then reactivate them one by one to see which Plugin is causing the issue.
If somehow the issue still persists, then provide us the permission to completely debug your Site which includes deactivating all the third party Plugins and removal of on-Site Customization changes too, so that we can thoroughly check this issue on your Site and assist you accordingly.
Best Regards