3790873 - Why are shared users or suppliers not deactivated when I run Load & Deactivate, and why does this differ between my parent and child realms?

I run the Import User Data (Consolidated) or Import Supplier Data (Consolidated) task with the Load & Deactivate operation. Shared users or suppliers that are absent from my import file are not deactivated, and they still appear active in the application. The behavior appears to differ between my parent and child realms, and I want to understand why.

fpc, federated process control, records deleted, site type, replicated user, shared object, deactivation reconciliation, parent site, child site , KBA , BNS-ARI-CP-CORE-IEX , Core Administration Import/Export , BNS-ARI-CP-CORE-SM , Core Administration Supplier Management , BNS-ARI-CP-CORE-UM , Core Administration User Management , Problem