Adding an expense doesn't allow Asset Stock account types

Adding an expense doesn't allow Asset Stock account types

Using the Purchases > Expenses function, I want to record the purchase of inventory. These inventory purchases are materials represented in a Stock account type (asset account) until they are incorporated into a job that is sold, when they will be transferred to Cost of Goods Sold (expense account).

Currently, the only account types available for entering a purchase in the Expenses module are:
  1. Cost of Goods Sold
  2. Expense
  3. Other Liability
  4. Other Current Liability
  5. Fixed Asset
  6. Other Current Asset
Why is Stock (asset account) not included when other asset accounts are? Could it be added?

Many purchases that go into stock do not require a bill to be made (like screws and fasteners that will be incorporated into jobs), so it would be appropriate to use the Expenses module for entering these purchases.

Update: the Stock account is also not showing up when trying to do a manual journal entry.