I can confirm the bug in my Acer Aspire 5920 model ZD1. In fact despite the fact that in System -> Preferences -> Mouse -> Touchpad there is "enable vertical scrolling" checked the touchpad scrolling doesn't run, but it runs with multimedia keys as you all sayd above.
I haven't yet tried the workaround posted by sNeo.
I can confirm the bug in my Acer Aspire 5920 model ZD1. In fact despite the fact that in System -> Preferences -> Mouse -> Touchpad there is "enable vertical scrolling" checked the touchpad scrolling doesn't run, but it runs with multimedia keys as you all sayd above.
I haven't yet tried the workaround posted by sNeo.