Inventory Slots brought with Story Token did not appear once redeemed. This may be an isolated problem and I believe the following conditions triggered the bug:

A) I redeemed when my inventory was overburdened (i.e.: 52/50)

B) Inventory previously brought with Plat gets overridden with the new Inventory Slots brought with Story Token, which may mean they cannot stack.

Devs PM for more info.