@Shane Corgatelli Thank you for reaching out to us, As I understand you are trying to investigate some resources are missing from the inventory in one subscription all of the key vaults are listed in the inventory but there are no storage accounts listed.
Would suggest to check for this setting within Key vault/Microsoft Defender for Cloud
If the Key Vault plan is listed as "partial" for a specific Key Vault resource, even though the plan is enabled at the subscription level, check the status of the Defender CSPM plan. If it is free, it is expected behavior. Partial usually occurs when one plan is standard and another is free.
Let me know if this answers your query, feel free to post back.