I'm trying to link to a service-backed record in a Post System Event to Feed

I'm trying to link to a service-backed record in a Post System Event to Feed node, and having difficulty for some reason. Per the documentation I'm using (what appears to be) the same ID field in both the Record Tag and dataSubset returned in the source expression. fldID is the unique identifier in my table and what I am trying to use here, but for some reason this is not creating the link. This was working fine before I converted from a entity-backed record to service-backed. Am I missing something here? I'm assuming the documentation "ID field of the dataSubset" is referring to the "identifiers" parameter? forum.appian.com/.../System_Functions.html

Record Tag:

=a!toRecordIdentifier(cons!SIR_RECORD,pv!CDT_SoftwareInstallRequest.fldID)

Data Subset:

a!dataSubset(
data: local!data,
identifiers: index(local!data, "fldID", {}),
startIndex: index(local!queryInformation.pagingInfo, "sta...

OriginalPostID-169441

OriginalPostID-169441