Hello,
Sorry to hear about the inconvenience.
So, can you please once try deactivating all the third-party Plugins on your Site. If the issue gets resolved, then reactivate them one by one to see which Plugin is causing the issue.
If the issue still persists, then please take a complete Backup of your Site first, then provide us the WP-ADMIN Login details of your Site and also provide 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.
.
