Item Class Security not recognizing custom roles in Redwood (26B) — anyone solved this?

Summary:

While testing our Redwood migration for Procurement, we noticed that users with custom roles can no longer see items in Redwood search (Agreements, Requisitions, Receiving). Only users with the seeded Product Data Steward role can see them - even a direct copy of Product Data Steward isn't recognized in Item Class Security. Trying to understand the right approach in 26B and whether others have run into similar behavior.

Content (please ensure you mask any confidential information):

Hi everyone,

We've been testing our Redwood migration for Procurement in TEST over the last few days and ran imto something pretty strange around item visibility.