Technical Blog Post
Storeroom tab in Security Groups app is not limiting access to storerooms
Storeroom information is used in transactions that affect inventory items and balances.
As a security measure, you can authorize a security group to make transactions with specific storerooms.
Storeroom authorization has never been meant to enforce whether or not a user can 'see' storeroom or inventory records.
Storeroom authorization really means financial storeroom authorization. ie: whether or not a user can affect the financial valuation of a storeroom.
A user who does not have storeroom rights should not be able to perform the following actions for any items in the storeroom: issue, return, transfer, balanace/cost adjustments, receipts, invoice variances.
You may also review the below documentation about Security Groups combination and Storeroom authorization rules:
Combination of security groups - rules for storeroom authorization
Authorizing access to storerooms for security groups