A shared note can embed an image stored anywhere in your vault, but Relay shares only the files inside the Shared Folder. If Obsidian saves the image to a vault-wide folder such as Attachments/, your collaborators receive the note without the image.
Set Obsidian to save new attachments next to the note you're working on, so they land inside the Shared Folder with it.
The file type also has to be one the Shared Folder syncs. Images, PDFs, and other attachments need storage on the folder's Relay Server. File types such as HTML also need Other files turned on for the folder on each device. For details, see Sync non-Markdown files and Storage for shared files.
We recommend this setting. Each folder keeps its attachments in its own subfolder.
Attachments, or another name you prefer.
For example, if your note is Projects/Website/meeting-notes.md, a pasted image is saved to Projects/Website/Attachments/. If Projects or Website is a Shared Folder, the image is inside it and syncs with the note.
If you don't want a separate subfolder, save attachments beside your notes.
The attachment setting applies to new attachments only. To share an attachment that's already outside the Shared Folder, move it in.
To move files faster, assign a hotkey to Move current file to another folder in Settings > Hotkeys.
If you keep attachments in a vault-wide folder on purpose, move each one into the Shared Folder when you want to share it.