I am not certain. All I know is I imported several notebooks (about 800 notes total), set a sync target to Dropbox, and I watched several times it said "deleted 1" during that time. And I hadn't changed, deleted, or created anything. I was waiting for it to finish less I might mess something up (some older sync systems were susceptible to this, doubted it was the case with Joplin, but wasn't about to take the chance either).
