iMovie play head jumps to start of clip when I try to split it on iphone

After searching and trying for hours, I found the reason for iMovie on iPhone (and iPad) jumping to the beginning when you try to split the movie by tipping at the playhead: the movie has to be in the split mode before. You have to tip on the scissors, scroll then to the desired position, tip again on the movie timeline and voila, the playhead stays in position and dies not jump back to the beginning. It drove me almost crazy...