The same happened to me today. All local files gone, files in the cloud (Onedrive) untouched fortunately. I purged insync (did not backup logs, dummy me…), installed the newest version 3.9.6.60027 for FC36, and am running a full resync now (~100gb). I am on OpenSuSE Tumbleweed.
Note: I have been with Insync for several years now (and paid for the original expensive Developer’s licence) and have not noticed much progress. Good thing is that Insync mostly works, except for occasional unexplainable duplicates, conflicts, and deleted files that I must recover in the cloud. Anyway, I believe that there is much room for improvement.
Haven’t you thought of a better business model that would allow for faster yet trustworthy development (like opensource)? It is about personal data afterall…