This seems to be the same problem that was flagged up in this thread from August 2016 and supposedly fixed then.
GarageSale keeps asking me if I want to relist items that were listed with Automatic restart, but which have since sold. I’ve opened the Inspector pane for the auction listings in question and unticked *Automatic restart8, but it’s still happening.
OSX 10,11,6
GarageSale 6.9.8 (634)