- πΊπΈUnited States tr Cascadia
No further reports of this behavior, and the Reply module hasn't been worked on in almost 10 years.
fivestar_field_prepare_view() is an implementation of the core hook hook_field_prepare_view(). I don't know of any situation that could happen to prevent core from invoking a valid hook function, unless fivestar.field.inc wasn't loaded into memory in the first place. Drupal 7 DID have problems with include files like this where they weren't always loaded when needed, but that's not something we can really track down here so many years after the fact.
If this continues to be a problem for someone, please open a new issue.