May i know after doing a synchronize did you again faced the problem.
I have synchronized, and then they are in the new folder.
I should check if then they also are at the old location.
Why do I myself have to synchronize? [It's software isn't it??]
You should not have to do the sync on the folder.
Mac or Windows? What version?
From the Lightroom About dialog, what exact version are you using (x.y.z)?
Its Mac, El Capitan.
I vaguely remember that previously in the previous MacOS, a move would indeed succeed in also moving the "images" and the files to the new folder.
With moving "images" I mean, that the catalogue shows them in the new place.
You might try upgrading to LR 6.3 and see if that fixes the problem.