I know the image sync not perfect. I have some design issue on this, for performance sake, sync document and image are separated downloading. However, this design causes some problems.
In ideal mode, if user create document in Mac(or iOS), then in another device, if user don't touch that document and can wait for a while, that image can be downloaded successfully. However, in most case, after document text synced (image is still downloading), user may typing something. That cause this problem: TextNut will stop to download that image because it treats that images is only in old version(the new version is just created because of the user typing in new device)
I will reconsider my design in future version and re-write that part code.