This morning after using Accordance on my laptop and closing it with the complete Dropbox sync I opened Accordance on my iMac. A message came up asking me to locate the file My Highlights.hlt. When I tried to locate it an error message reading "I/O error #0 in Accordance Files" came up and then Accordance opened anyway. When it did open Accordance automatically created a new file, My Highlights 2.hlt, which was empty and set to default settings. Confused, I closed Accordance and tried again with the same result so that there was also a My Highlights 3.hlt and then a My Highlights 4.hlt. At some point in the process the original My Highlights.hlt, which had been visible in the file folder, disappeared from my computer. I could no longer find it at all with Spotlight or in the Trash. Before it disappeared it had a strange quality to it in that when viewed in Finder the icon was a white rectangle instead of the usual Accordance icon. Also, when I used the 'get info' option, under 'Open with' the 'Accordance (Default)' choice was visible, but sort of transparent and unavailable to modify. This is in contrast with the new My Highlights X.hlt files where it was possible to access and modify what was under 'Open with.'
As far as I can tell it is too late to do anything about it and I've lost all my highlights and custom highlight settings which I've been keeping as I do my dissertation research. If it isn't too late, let me know. In any case, there seems to be a bug that should be fixed.