It probably got overlooked. Though there are rules against bumping, the delay is only 24 hours. (Although those that just type bump tend to get criticized.) As is mentioned in the posting guidelines, always good to post, and, I tried this and that.
Or it might have been that at the time, anyone who saw it didn't have a good answer. Surprised this got overlooked though, I would think that there might have been some solutions.
Sometimes, folks are just busy, see one, and while, on a slow Sunday, they might type, Gee, that's a tough one, on a busy workday they might not. May 10th was a Thursday.
Anyway, there are a few possibilities--I got most of mine from the Arch wiki https://wiki.archlinux.org/index.php/Touchpad_Synaptics
A thread I started on the UX31A mentions a couple that I found useful.
in post 6.
Should have added, try synclient -l to see if it's recognized by a synaptic driver. If not, then all I can think of is the GUI things that you've mentioned that you tried.