Workflow start when detect change not work

Hi all

i use sharepoint online server. 

i have workflow which is update field in directory.

update is make, and change date is change too on my directory for this file.

I have workflow to this directory which si start only on change... but it not start when change come from update. if i do change manualy and save.. here workflow start.

do you know why ?

tks advance

EDIT

I use step WAIT parameter on the first workflow (item create), and it's work.