FFF sorts most list metadata entries by default. You can ask it not to with the setting
keep_in_order_entryname:true Changing entryname as appropriate, of course.
In AO3, genre includes
freeformtags and
ao3categories, so I expect you'd need three keep_in_order_ settings, one for each of them plus
genre:
Code:
[archiveofourown.org]
keep_in_order_freeformtags:true
keep_in_order_ao3categories:true
keep_in_order_genre:true
I haven't played with those setting recently, but that's how I recall it working.