diff --git a/x-pack/plugins/observability_solution/observability/public/components/alert_overview/helpers/map_rules_params_with_flyout.ts b/x-pack/plugins/observability_solution/observability/public/components/alert_overview/helpers/map_rules_params_with_flyout.ts
index fce4bd35dbdee..2ecda6419a06f 100644
--- a/x-pack/plugins/observability_solution/observability/public/components/alert_overview/helpers/map_rules_params_with_flyout.ts
+++ b/x-pack/plugins/observability_solution/observability/public/components/alert_overview/helpers/map_rules_params_with_flyout.ts
@@ -269,7 +269,7 @@ export const mapRuleParamsWithFlyout = (alert: TopAlert): FlyoutThresholdData[]
       const { thresholdComparator, threshold } = ruleParams as EsQueryRuleParams;
       const ESQueryFlyoutMap = {
         observedValue: [alert.fields[ALERT_EVALUATION_VALUE]],
-        threshold: threshold.join(' AND '),
+        threshold: [threshold].flat().join(' AND '),
         comparator: thresholdComparator,
         pctAboveThreshold: getPctAboveThreshold(
           threshold,