Hello!
‘Layout options → Page Setup → Flows → Flow heading top margin’ actualy changes bottom margin, and vice versa: ‘Flow heading bottom margin’ changes the space between flow heading and music that belongs to this flow.
Welcome to the forum @mbsrz.
It’s unlikely that there is a bug. I’m sure someone with a reasonable amount of knowledge on this topic will have more information for you.
Ah ok, now I understand. I mixed up meaning of ‘Flow heading top (and bottom) margin’ and ‘Flow [music] top (bottom) margin’ because Page Setup Layout Options there are Page Margins, Music Frame Margins and this. So consequently I expected Flow margins not Flow heading margins next.
Thanks.