Defender for Cloud Asset Inventory shows only 1 resource — Foundational CSPM enabled but discovery not populating

I have Foundational CSPM enabled on an Azure subscription with approximately 28 resources, but the Defender for Cloud Inventory page only displays 1 resource (an auto-created Log Analytics workspace). I'd like help getting discovery to populate the full inventory.

Configuration confirmed via az security pricing list:

• FoundationalCspm — pricingTier: Standard (enabled)
• Discovery — pricingTier: Standard (enabled)
• All other Defender plans — Free (intentionally not enabled at this time)
• freeTrialRemainingTime on FoundationalCspm is 0:00:00, confirming the plan has been enabled for an extended period

Resources in the subscription confirmed via Azure Resource Graph (az graph query): 28 resources, including multiple App Services, an App Service plan, a PostgreSQL flex server, a storage account, a VNet, and supporting infrastructure. All resources are in a single resource group in Canada Central.

Expected: Per Microsoft Learn documentation, Asset Inventory should list all assessable Azure resources within minutes of enabling Foundational CSPM.

Actual:

• Defender for Cloud → Inventory shows Total resources: 1 — only the auto-created DefaultWorkspace-... Log Analytics workspace
• All Inventory filters set to "All" (Subscription, Resource type, Resource group, Environment)
• Recommendations page also empty across all resources
• Behavior has persisted; this is not a "just enabled, scan hasn't run yet" situation

Already tried:

• Confirmed all UI filters are cleared
• Confirmed correct subscription scope
• Verified resources exist via Resource Graph (returns full list of 28)
• Confirmed pricing tier via Azure CLI as noted above

Looking for:

• Guidance on forcing CSPM policy-based discovery to re-initialize
• Or a root-cause diagnosis for why discovery isn't enumerating resources

Happy to share subscription ID and additional config detail privately if an engineer engages on the post.