Why aren’t my Markdown images showing?
Download the Portable Docs Lab. In docs/overview.md, the image path is ../assets/reading-path.svg: start in docs/, go up once, then enter assets/. Opening only overview.md from a different location leaves that path behind.
When a local image is missing, first confirm the file exists at the resolved path. Then check spelling, capitalization and extension; Map.svg and map.svg need not be the same file on every filesystem. If the Markdown is part of a ZIP, extract the whole ZIP before testing. A path to file:///Users/another-person/... is tied to their machine and should be replaced with a relative path inside the package.
How do I test an image path?
Place test.md and picture.svg side by side, then add  to the Markdown. If that works but the original image does not, compare the original path and filename. If the minimal file also fails, check whether your viewer supports that image format and whether it has permission to reach the folder.
The free online reader intentionally never loads document images, so it is not a valid test of image-path support. Finder Quick Look extensions may have different access boundaries from a full app; do not infer the behavior of one from the other.
What Aero Markdown shows
Open the folder that contains the Markdown and the image with File → Open Folder…, or press Command-Shift-O. You can also drop that folder on the window. A sibling image can show when you open only the Markdown file, because that file’s own folder is then the boundary. A path that climbs out of that folder, such as ../assets/reading-path.svg in the Portable Docs Lab, needs the package folder opened.
Images appear on the rendered page. If the window is showing the source, choose Reading Mode (Command-Shift-E). While editing, Show Preview Beside Source shows the picture beside the source.
A readable png, jpg, jpeg, gif, webp, or svg inside that opened folder appears on the rendered page.
An http or https image is not fetched. A file outside the opened folder, a file the app cannot read, or a different extension does not appear as a picture. With no alt text, a remote address shows “Remote image not loaded” and the other misses show “Image unavailable”. With alt text, the missing figure shows that text. Download and checkout are not available yet.
Once the image resolves, test a copy of the entire folder in a new location. The portable-document guide explains why this matters for handoff.