We have identified that audit log reports link not available for SharePoint Online OneDrive for business and mysite. The same link as in the screenshot is available for other SharePoint Online sites. This seems to be an issue since we can enable the audit logs but could not view the logs.
We have been working with Microsoft and as described in O365 roadmap that this seems to be as designed and will be placed in different Compliance Center. “User activity reports will allow you to audit SharePoint and OneDrive for Business user actions such as views, edits, deletes, downloaded files, and sharing of files. These reports will be available in the Compliance Center.”
Well, at this time the workaround is to append the report page URL like “_layouts/15/Reporting.aspx?Category=Auditing” to the mysite or OneDrive for business site to view the reports. Here is one example to view the audit logs from my OneDrive for business site.