Aha, thanks, and sorry for bug reporting due to poor user knowledge. Turned PDF Autoscroll on and now it is working as expected.
I had done some experiments with automatic PDF scrolling of note sheets, but turned it off, because I couldn't get it to match the slow tempo of the song.
When I then introduced time-stamp based scrolling I didn't think it would fall under the category "Autoscroll", so I forgot to turn it on.
Regards, and keep up the good work!
Ulf