According to One Mile At A Time
blog:
American’s stopover policy has long been that you can have a free stopover at your international gateway city on an award, even on a one-way.
Well, overnight it appears that’s no longer the case anymore either. You can’t have a stopover on a one-way award anymore, and if you try to change the date of an existing “stopover” segment it will price the segments separately.
The changes are bad but not necessarily unexpected. The lack of any advance notice is horrid. But this last part seems to be over the top: if you've flown an international trip and are currently on the stopover, you were holding a one way domestic ticket with free date changes. Now if you want to change the date, your domestic ticket becomes worthless? Changed rules on an already issued ticket?