The wiki pages get created in their own Git repository and the image files are also added there. You can browse the repos from within DevOps at; https://dev.azure.com/MyOrganisation/MyProject/_git/MyProject.wiki
The markdown path for the image should begin /.attachments/
and make sure if you are adding dimension you use =500x
and not =500
if you exclude the height e.g.

For more info, click here.

