Hello,
Could you please once try checking with the Parent Theme activated first? If it gets resolved, it seems that there is some issue with your Child Theme customization then you need to reconsider that.
If the issue persists, then once try deactivating all the third party Plugins on your Site 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.
As your Site is Live, we are suggesting these changes to you to try first.
If somehow issue still persists, then please take complete Backup of your Site first, then provide us the 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