I set up a Test user from a clean base and put the supplied version of garage sale (GarageSale_7_2018-02-13_1.dmg) into it. I set a dummy listing into the scheduler and watched what happened.
On the Console there was no record of “Schedule Timer Fired” on the system log. (As with my main setup)
Listings would not launch from a dock minimised scheduler (as with my main setup)
However, I then found an update to GS version 7.0.13b2 and found that this would launch listings from a dock minimised scheduler; so have now downloaded that version on my main user base, and have now tested that satisfactorily - at least when launching from a dock minimised scheduler. I haven’t yet found the courage to try it from sleep mode!
I don’t know what you did but the new version appears to have rectified at least part of the problem
but updated to