diff --git a/.github/workflows/pr-preview-deploy.yml b/.github/workflows/pr-preview-deploy.yml
index 6858a7cb5..ba8a74b76 100644
--- a/.github/workflows/pr-preview-deploy.yml
+++ b/.github/workflows/pr-preview-deploy.yml
@@ -33,7 +33,7 @@ jobs:
           ssh://git@github.com/
 
       - name: Install npm Packages
-        run: npm ci
+        run: npm i
 
       - name: Generate environment file
         run: npm run env
diff --git a/src/app/op-log/sync/immediate-upload.service.ts b/src/app/op-log/sync/immediate-upload.service.ts
index ee5309215..92ae4ba09 100644
--- a/src/app/op-log/sync/immediate-upload.service.ts
+++ b/src/app/op-log/sync/immediate-upload.service.ts
@@ -1,11 +1,12 @@
 import { inject, Injectable, OnDestroy } from '@angular/core';
 import { Subject, Subscription } from 'rxjs';
-import { debounceTime, exhaustMap, filter } from 'rxjs/operators';
+import { debounceTime, exhaustMap, filter, take } from 'rxjs/operators';
 import { isOnline } from '../../util/is-online';
 import { SyncProviderManager } from '../sync-providers/provider-manager.service';
 import { OperationLogSyncService } from './operation-log-sync.service';
 import { isFileBasedProvider, isOperationSyncCapable } from './operation-sync.util';
 import { OpLog } from '../../core/log';
+import { DataInitStateService } from '../../core/data-init/data-init-state.service';
 
 const IMMEDIATE_UPLOAD_DEBOUNCE_MS = 2000;
 
@@ -46,11 +47,23 @@ const IMMEDIATE_UPLOAD_DEBOUNCE_MS = 2000;
 export class ImmediateUploadService implements OnDestroy {
   private _providerManager = inject(SyncProviderManager);
   private _syncService = inject(OperationLogSyncService);
+  private _dataInitStateService = inject(DataInitStateService);
 
   private _uploadTrigger$ = new Subject<void>();
   private _subscription: Subscription | null = null;
   private _isInitialized = false;
 
+  constructor() {
+    // Initialize only after data is loaded to avoid race condition where
+    // upload attempts happen before sync config is loaded from IndexedDB.
+    // This prevents 404 errors to default baseUrl during app startup.
+    this._dataInitStateService.isAllDataLoadedInitially$
+      .pipe(filter(Boolean), take(1))
+      .subscribe(() => {
+        this.initialize();
+      });
+  }
+
   /**
    * Initializes the immediate upload pipeline.
    * Call once after app initialization.
diff --git a/src/main.ts b/src/main.ts
index b4b67fec0..2aa57addd 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -41,7 +41,6 @@ import { StoreModule } from '@ngrx/store';
 import { META_REDUCERS } from './app/root-store/meta/meta-reducer-registry';
 import { setOperationCaptureService } from './app/root-store/meta/task-shared-meta-reducers';
 import { OperationCaptureService } from './app/op-log/capture/operation-capture.service';
-import { ImmediateUploadService } from './app/op-log/sync/immediate-upload.service';
 import { EffectsModule } from '@ngrx/effects';
 import { StoreDevtoolsModule } from '@ngrx/store-devtools';
 import { ReactiveFormsModule } from '@angular/forms';
@@ -182,17 +181,9 @@ bootstrapApplication(AppComponent, {
       deps: [OperationCaptureService],
       multi: true,
     },
-    // Initialize immediate upload service for real-time sync to SuperSync
-    {
-      provide: APP_INITIALIZER,
-      useFactory: (immediateUploadService: ImmediateUploadService) => {
-        return () => {
-          immediateUploadService.initialize();
-        };
-      },
-      deps: [ImmediateUploadService],
-      multi: true,
-    },
+    // Note: ImmediateUploadService now initializes itself in constructor
+    // after DataInitStateService.isAllDataLoadedInitially$ fires to avoid
+    // race condition where upload attempts happen before sync config is loaded
   ],
 }).then(() => {
   // Initialize touch fix for Material menus