I have tested HOS 1.27-Public. Max corruption for Viki on that version is 360 corruption. I have also tested buying catwoman outfit before viki is talking about her new batgirl costume. I have no problems to trigger the cosplay event. When viki reach 210 this triggers the new swimsuit event for her, speaking after this again with viki in school triggers the batgirl dialog in school. Buying catwoman costume and call viki from kelly´s home starts the cosplayevent with viki. If you meaned 1.28-Patreon, because you said Viki is 400 corruption, i currently can´t say, if there is a bug or not to trigger the cosplay.