Set-PnPBuiltInSiteTemplateSettings error "Attempted to perform an unauthorized operation"

[a-goo]

Logged in as Global Admin. New PnP authentication approval, so it's all the latest management shell permissions.

PS C:\Users\a-goo> Connect-PnPOnline -Url $AdminCenterURL -Interactive
PS C:\Users\a-goo> Set-PnPBuiltInSiteTemplateSettings -Identity 00000000-0000-0000-0000-000000000000 -IsHidden $true
Set-PnPBuiltInSiteTemplateSettings: Attempted to perform an unauthorized operation.

Same error when attempting to hide only one template.

If I have what seems to be sufficient permissions, what's missing?
This error is too generic.

The specified permissions here: https://pnp.github.io/powershell/cmdlets/Set-PnPBuiltInSiteTemplateSettings.html

"Required Permissions
SharePoint: Access to the SharePoint Tenant Administration site"

Are obviously incorrect or misleading. A Global Admin shouldn't need to explicitly be granted the SharePoint Admin role for this to work.