Config split settings file generated into split directory

Drupal 8.7 I have a multisite split. The config_split.config_split.<sitename>.yml files are supposed to go into the config/default directory. For some reason when updating a split on one of my sites, instead of updating the existing file in that location, it creates a new file in the config/sitename directory. It only does it on this one site. When I compare the newly generated file to the one for that site in the default directory, only the new changes are different. The rest is the same.