From a ticket we learned that UKG Pro data is synced with Priority First Sync (PFS) and that PFS synced data is never later checked (even if during a resync) to determine if the record still exists in the source, and as such deleted records are never updated to indicate that they have been deleted (_fivetran_deleted = true).
This is a request to alter that strategy.  If data is re-synced from the source, even PFS data needs to be examined to determine if it still exists.  When a record is missing from the source system, the standard deletion logic (either soft or hard deletion) must be followed.