diff --git a/docker/telemetry/otel-collector-config.yaml b/docker/telemetry/otel-collector-config.yaml
index 60f59e7c48..d0e231f6d6 100644
--- a/docker/telemetry/otel-collector-config.yaml
+++ b/docker/telemetry/otel-collector-config.yaml
@@ -119,15 +119,18 @@ processors:
   #   - resource_group: node id, optionally suffixed with network type. The id
   #     is always present; network may be absent, so it is appended separately
   #     to avoid a trailing separator.
-  # Concat is guarded on presence because OTTL Concat renders the literal text
-  # "<nil>" for an absent attribute (it does not skip it).
+  # Concat is guarded on presence (!= nil and != "") because OTTL Concat renders
+  # the literal text "<nil>" for an absent attribute and would emit a stray
+  # separator for an empty one. The perf-iac collector stamps these attributes
+  # with an empty-string default when a run has no work item, so the empty-string
+  # check matters, not just the nil check.
   transform/legendgroups:
     metric_statements:
       - context: resource
         statements:
-          - set(attributes["iac_group"], Concat([attributes["xrpl.branch"], attributes["xrpl.node.role"], attributes["xrpl.work.item"]], "-")) where attributes["xrpl.branch"] != nil and attributes["xrpl.node.role"] != nil and attributes["xrpl.work.item"] != nil
-          - set(attributes["resource_group"], attributes["service.instance.id"]) where attributes["service.instance.id"] != nil
-          - set(attributes["resource_group"], Concat([attributes["resource_group"], attributes["xrpl.network.type"]], "-")) where attributes["resource_group"] != nil and attributes["xrpl.network.type"] != nil
+          - set(attributes["iac_group"], Concat([attributes["xrpl.branch"], attributes["xrpl.node.role"], attributes["xrpl.work.item"]], "-")) where attributes["xrpl.branch"] != nil and attributes["xrpl.branch"] != "" and attributes["xrpl.node.role"] != nil and attributes["xrpl.node.role"] != "" and attributes["xrpl.work.item"] != nil and attributes["xrpl.work.item"] != ""
+          - set(attributes["resource_group"], attributes["service.instance.id"]) where attributes["service.instance.id"] != nil and attributes["service.instance.id"] != ""
+          - set(attributes["resource_group"], Concat([attributes["resource_group"], attributes["xrpl.network.type"]], "-")) where attributes["resource_group"] != nil and attributes["xrpl.network.type"] != nil and attributes["xrpl.network.type"] != ""
 
 connectors:
   spanmetrics: