Editing a pattern part of a "follow chain"

I can’t seem to fitnd the way to keep, in step mode, fixed on the grid, the display of a pattern I want to do edit.
It is ok when follows are linear and patterns lengthy enough, but when adding randomisation in follows 1 & 2…

Sounds weird, but I searched the manual, and tried different combos.

Any one has a solution-hint ?

Cheers !