1. Create an image and give it an uppercase file extension (e.g. test.PNG)
2. Attach the image to the Notebook

The image will either show as a broken link or fail to attach and these errors appear in the console :

Failed to fetch: TypeError: Failed to fetch
file: Refused to load resource c:\Users\chgagnon\Desktop\test.PNG from file: protocol (original URL: file:///C:/Users/chgagnon/Desktop/test.PNG)

If I change the URL in the notebook to lowercase (![](c:\src\AzureDataStudio\extensions\notebook\test.png)) then it works fine. (on Windows at least)