I have noticed that after I delete a directory, if I later create another directory with the same path and name, Insync also deletes this directory without checking its timestamp and comparing to when the deletion was performed.
Specifically: I deleted directory A in location B, then moved directory C to location B and renamed it A. Directory C was deleted. Luckily I was able to recover C from .insync-trash, restored C in another location, waited for Insync to finish synching all the changes (one week later), and moved C back to location B. Insync immediately deleted C again.
This is alarming as I have been using Insync for a long time now, and can’t possibly remember all the files/directories I have deleted. The above case was one I noticed, but if I do not notice the deletion before .insync-trash is cleared, the files would have been unrecoverable (they were also deleted from Drive and were not in the Drive trash).
Not sure if this issue is distribution/version specific, but I am using 1.4.5 for on Ubuntu 16.04.