My apologies - this is a known bug and has been reported to Magix, this is what happens with my installation - the control is highlighted in the image below.
John EB
Former user
wrote on 9/20/2023, 5:36 AM
@Konstiantyn-Rudoi Hi, as John says this is a known bug but it can be used, sort of.
Click & hold on the little line, then slide your mouse up & down.