The short answer is that OneDrive API won’t allow you to sync over 4MB.

If you are in the desktop app, you can click Tools>Resources and look for files over 4MB and delete them then re-sync.

A work around is to upload your file(s) to OneDrive. Go to OneDrive and copy the share link for that file and then embed that link into your Joplin note. Not as simple as adding it Joplin. Oh Well.

Does anyone have a better solution?