This usually happens because certain URLs (which are used to fetch thumbnails) are not added in the trusted URLs. To resolve this issue, follow the steps - 

Once this is added, your thumbnails should start working correctly. See image below for reference.

How to get CloudFiles API key

Thumbnails not working in LWC

How to integrate Azure Blob storage with CloudFiles

CloudFiles Salesforce

Salesforce

Installation guide

Connect external folder to a record

Access, share and track a file

Share files in experience cloud (community)

Document Generation with CloudFiles

Quick Starts

Document Generation Test Drive

Automatic Folder Structures Test Drive

Nested Folders based on Object Relationships Test Drive

Template Folder Cloning Test Drive

Move SFDC Files to External Storage Test Drive

Copy Email Attachments to Case Folders Test Drive

Custom Object Creation on File Upload Test Drive

Move Lead folder to Account folder on conversion

CloudFiles Widget Configurations Test Drive

Update Sharepoint Folder Name Test Drive

Document Management & Sharing Test Drives

Document AI Playground Test Drive

KYC Upload Checker using AI

Business Document Fields & Line Items Extractor

Document AI Test Drives

Test Drive

Adding CloudFiles widgets to Salesforce Classic

Automations

Content Library

CloudFiles Permissions

CloudFilesUploader Component

Content Library Widget

CloudFiles Uploader Widget

Document AI Playground Widget

Document Generation Widget

Experience Cloud Widget

Internal Record Widget

Widget Configuration Guide

CloudFiles Widgets Guide

Document Generation configuration

Embed CloudFiles widget in custom lightning web components

Field Service Lightning Support

Image Resize Feature

Using a service account

Features

Copy Resources

Copy Salesforce Files

Create Attachment

Create File Connect Files

Create Folder

Create Folder (Async)

Create Microsoft Team

Create Salesforce File

Create Salesforce Files (Batch)

Create SharePoint Site

Delete Attachment

Delete Resource

Get Attachments

Get Connected Folder

Get Files Connect Resource Id

Get Folder Contents

Get Resource Details

Get Resource Property

Get Salesforce Files

Move Resource

Search by Resource Metadata

Set Resource Property

Set Resource Property (Batch)

Update Permissions

Doc Management Flow Actions

Create Dataroom

Add to Dataroom

Create File Request

Create Link

Update Link Settings

Share With Community User

Remove from Community

Doc Sharing Flow Actions

Generate Document

Generate Document (Sync)

Generate Document  (Batch)

Merge Documents (Sync)

Doc Generation Flow Actions

Process Document using AI

Query Document

Query Document (Batch)

Split Document using AI

Doc AI Flow Actions

Assign User Licenses

Unassign User Licenses

Get Event Details

Delay

Misc Flow Actions

Flow Actions

Custom Object Mode Flow Setup

Platform Event Mode Flow Setup

Intercepting CloudFiles Events

Content Version Created

Content Version Created Batch

Salesforce File Copied

Salesforce File Attached

Folder Created

Document Split

File Received

File Replaced

File Viewed

File Uploaded

Resource Attached

Resource Updated

Document Generated

Document Processed

Error Event

Resource Cloned

Resource Deleted

All Event Types

Events

Create Automated Folder Hierarchies for Managing External Files from Salesforce Objects

Automated nested folders creation based on object relationships

Automatically moving files from Salesforce storage to external storage

Copy Email Attachments to Case Folders in external storage if Email-to-Case is activated

Renaming a folder in Sharepoint when the Record is updated

Document Management Tutorials

Document Generation Tutorials

AI Flows - Initial Setup Guide

Using AI for Simple Data Extraction from KYC Files

Batching AI Queries

Line Item Extraction

Classify and Rename Uploaded Files

AI-Powered KYC Upload Checker

Document AI Tutorials

Tutorials

Installing from the Salesforce AppExchange

What's In the Package?

Installation

CloudFiles Account Setup

Template Builder Setup

User Management

Configuration

Document Generation LWC

Template - Resources

Template - Actions

Template Creation

Generating Documents

Document Generation

What's in the Package ?

Technical Requirements

External Storage / Library Configuration

Branding Setting

Link Defaults

Utilize CloudFiles widget in Custom Screen Flows

Widget Flow Actions in CloudFiles

Document Management & Sharing

What's In the Package

AI Playground

Usage

Document AI

Platform Events Apex Handler (Object Type)

Platform Events

Add To Dataroom

Create Attachments

Create Content Version Batch

Create Datarooms

Create File Requests

Create Folders

Create Folders Async

Create Links

Get Preview URL

Move Resources

Update Resources

CloudFiles Client

Attachment

ContentVersionCreated

ContentVersionCreatedBatch

Dataroom

DocGen Params

DocumentGenerated

DocumentProcessed

DocumentProcessedError

DocumentSplit

ErrorEvent

Event

FileReceived

FileReplace

FileRequest

FileUpload

FileViewed

FolderCreated

Generated Document

Input & Output Types

Link

Resource

ResourceAttached

ResourceCloned

ResourceDeleted

ResourceUpdated

Resource List

SalesforceFilesAttached

Types

Apex