v18 Object Entitlement / Permission Changes?

A customization that we wrote for one of our customers worked fine up through v17 of SaaS. With V18 rollout, objects in the range of 50000 - 99999 are no longer accessible by our users.

We’ve set up RIMD / X permissions on all objects through the PermissionSet object. We can see that these have been installed through the Permission Sets and User → Effective Permissions pages.

However, the Effective Permissions show “Conflict” for the object permissions. Clicking any of the “Conflict” links shows an error that starts with “This user has been given the Yes permission for the selected object, but the object is not included in their license.”

Has something changed with V18 entitlements for objects in 50000-99999 range? Or am I missing an assignment to Business Central Essentials somewhere in my code?