Subscription will be suspended, but no storage in use

[GarethOakleyTM]

We recently setup Google Cloud Identity (free) as part of getting access to various documents on the Google Developer portal. We don't intend to use Google Drive, and we've blocked users from accessing it. However, we're seeing a warning that our Google Cloud Identity subscription is going to be suspended because we're using storage space:

If I look at the storage report though:

I can't see which user has any storage in use, and I can't contact support. We also use managed accounts for access to the Google Play console, so it's kind of urgent that we don't get suspended. Any ideas?