Originally slated for release May of this year, the Steam version of Disgaea 5 Complete was delayed to Summer 2018 just a day before release due to some sort of unnamed issue.
After months of no word about the game, NISA tweeted that they would have an announcement about the game during Anime Expo. The announcment was made that Disgaea 5 Complete was delayed again to Fall of 2018, with another round of beta testing beginning in October. An official tweet confirms the delay:
Sorry to hear you were not able to catch our announcement! Disgaea 5 Complete on PC is going to be released in Fall 2018 and will have a private beta starting in early October. We appreciate everyone's patience while we worked out the issue we found earlier this year.
— NISAmerica (@NISAmerica) July 9, 2018
The issue in question still remains a mystery.