Well, my conversion is complete but all of my inline images are missing.
They all seem to have been converted to this:
![]
(webman/3rdparty/NoteStation/images/transparent.gif)
Examining a particular note and comparing it to the original in Synology Note Station, looking in the attachments subfolder for the converted notebook, I can see that the image (PNG file) is there, but correctly linking to it seems to have failed.