From 6de4b8d39e942957fdb482e395056e0c16fd0f2c Mon Sep 17 00:00:00 2001
From: Ian MacDougall Murray <i-murray@users.noreply.github.com>
Date: Wed, 4 Mar 2026 17:35:06 +0000
Subject: [PATCH] fix: flatten outputs before building loadingOutputs

Fixes #3619
---
 dash/dash-renderer/src/actions/callbacks.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/dash/dash-renderer/src/actions/callbacks.ts b/dash/dash-renderer/src/actions/callbacks.ts
index ee3a251378..37aab3f194 100644
--- a/dash/dash-renderer/src/actions/callbacks.ts
+++ b/dash/dash-renderer/src/actions/callbacks.ts
@@ -791,7 +791,7 @@ export function executeCallback(
         }
 
         const __execute = async (): Promise<CallbackResult> => {
-            const loadingOutputs = outputs.map(out => ({
+            const loadingOutputs = flatten(outputs).map(out => ({
                 path: getPath(paths, out.id),
                 property: out.property?.split('@')[0],
                 id: stringifyId(out.id)