Review the HTML code for your email signature to make sure the image tag is correctly formatted. It should look something like this:
<img src="https://www.example.com/logo.png" alt="Company Logo">
Replace the URL with the actual URL of your image.
Outlook has security settings that can block external images for privacy and security reasons. To check these settings, go to File > Options > Trust Center > Trust Center Settings > Automatic Download. Make sure the option "Don't download pictures automatically in HTML email messages or RSS items" is not selected.
Ensure that you are using an up-to-date version of Outlook. Outdated versions may have compatibility issues.