/home/pi/.attract/attract.cfg if you installed AM from the command line.
/opt/retropie/configs/all/attractmode/attract.cfg if you used the RetroPie setup menu.
IMO - There are quirks/drawbacks/issues using the RetroPie setup menu to install AM. If you recently "upgraded" AM (or everything) in the RetroPie setup menu, it's likely your issue.