There are a few reasons items could have a status of "Not Available." Some came about through the migration to Alma from Aleph if there was a Item Processing status in Aleph of "In cataloging". Others are from Alma, when during the invoice payment process the item is received, Alma automatically assigns it a status of "In transit", and the item displays as "not Available'. This has the consequence of suppressing the Aeon request in Hollis and indicating to a researcher the item is not available for use.
To fix the problem of an item not showing up as "Available"
Copy the barcode of the item
Change your location to the correct Circulation Desk (Houghton or Theatre)
Go to Fulfillment to "Scan in Items" (under Resource Request). Uncheck "Register Inhouse use" and scan in barcode. That will remove the "In Transit" and change the Item status to "Available".