Sync Records Smart Service limited to 100 records when used with a Service-Backed Record

When using the Sync Records smart service in a process model targeting a service-backed record type, the node appears to only sync the first 100 records (and returns 100 as “Records Updated”) even when I pass more than 100 identifiers.

1. Manual sync on the record type successfully syncs all records and respects batching.
2. Scheduled sync also syncs all records.
3. Smart service only ever syncs the first 100.

My integration and sync expression pages correctly and return more than 100 records when called independently, and there is no documented 100-record limit in the Appian documentation.

Has anyone else found this to be the case when it is stated to work with up to 1000 records (and does when used with non service-backed records)

Thank you.