I went ahead and decided to do the nightclub boss fight since I never beat it in the update prior to the arcade early access update, so I don't know if this is a bug with the update, but whenever I beat the nightclub boss fight in the current update, it freezes here. The game still runs and the characters are still moving, but the game doesn't send me back to the menu or show me a cutscene or whatever is supposed to happen once you beat the boss night.
I don't know if this is a bug with the update or my computer or something, but I figured I'd just share this here.
This is also on the steam version of In Heat and the platform is windows.
The issue I had with the game freezing after the first phase of the fight was fixed, however it appears that I also have the same issue now, where after the cutscene I get a black screen and music plays, like you. The best option is to just wait for another hotfix to be released.
Bugs like this are to be expected when a game has a major update though, I'm sure the developers will release another hotfix to fix the issue soon, so I'm just gonna wait for it. The Nightclub boss fight isn't that challenging so I don't mind having to replay it whenever it bugs out like this.