You may not receive email alerts for nudity for Gmail attachments if:

You have not unchecked the ‘Remove attachments from message’ field inside your Aware route setup. Without this, the Aware server will not receive any Gmail attachments to scan.
Log in to your Google Workspace admin console at admin.google.com and click on 'Apps'.
Click on 'Google Workspace'.
Click on 'Gmail'.
Scroll down to 'Advanced settings' and click on it.
Scroll down to 'Routing' and click on 'Edit'.
Under 'Edit settings', scroll down to 'Recipients' and click on 'Edit'.
Uncheck the checkbox beside 'Remove attachments from message' under 'attachments' and click on 'Save'.
Again, click on 'Save'.
Click on 'Save' again to complete the process.
You have switched off the Aware email notification from your Account Settings. Please check your Aware email alert account settings.

Or it might be that your students are not sharing nude images with each other via Gmail (great kids!).

Why am I not receiving any email alerts for nudity for Gmail attachments?