There seems to be a bug with the victory screen where the victory music plays and the character portraits appear but the experience bars don't, preventing me from moving on from the battles with the only thing I can do being closing the game and just avoiding the fights. Idk if that's what you meant by a black screen at the end of Runt Whiner's fight, but it happens at the end of the regular fights in the forest here, the difference being for them, it just stays stuck, where for Runt Whiner, there seemed to have been a 5-10 second delay before the experience bars showed up in the victory screen of his fight.
Viewing post in Small On Top 0.24.1 - bug fixes. comments
Does the game work with a new save file? This feels like a thing that's not caused by the game itself?
Are you sure you're not pressing the ctrl to hide text? This really is the first time I've heard about a problem like this. It really feels like it's a PC side problem, like something is slowing it down. Have you updated your drivers? Have you tried playing the game as an administrator?
I'm really sorry, I don't know how to help :(