If you can't find the Stock module, or the Reconcile option, when editing a security profile in Access Supply Chain, this is expected. This article explains why, and how to grant access to Stock options instead.
Why Stock isn't in Security Profiles
The Security Profiles screen (System, Security Profiles) only controls Financials modules. This is why you'll see options like Nominal Ledger, Sales Ledger, Purchase Ledger, Cash Book and Costing listed there, but not ERP modules.
Stock, along with other ERP areas such as SOP and POP, is an ERP module. ERP module access isn't set in Security Profiles at all. It won't appear there no matter how far you expand the module list.
How ERP module access is controlled
Access to ERP options like Stock is controlled by the menu assigned to a user's profile, not by the Financials-focused Security Profiles screen.
To grant a user access to Stock Reconcile, you have two options:
Add the user to an existing profile that already has access to the option you need.
Amend the menu assigned to the user's profile to include the required option.
Amending menus is usually carried out by Professional Services, unless you have someone in-house who is familiar with making these changes.
Checking which profiles already have an option
There's no single screen that lists this directly. If you know a user who already does a similar job to the one you're setting up, the simplest approach is to give the new user the same profile.
Otherwise, go into the forms designer and look at specific form sets to see which profiles have access to a given option.
Related issues
If ERP modules are missing for a user more broadly, not just Stock, this can also indicate the user was created without the correct database rights, or a local display or cache issue on their PC.