I’ve tried two options.
The non-global version linked here: [Special K] Render Quality and Performance Settings SEGA Forgot - [Updated: 8/10/18] :: Yakuza 0 General Discussions
The Oct 2020 global version.
Both versions do this: Force the game into windowed mode, taking up almost all of 3840x2160 but leaving a small unused area of a few pixels on all sides. The non-global version works the best, in that it allows the game to display graphics, but the moment I try to open the SpecialK menu to perhaps see why it’s forcing windowed, I hit a wall. The menu opens, along with the you-must-agree window, but the mouse pointer is frozen. And when I click a button, the entire game task acts like it cannot proceed (goes semi-white with the Windows hourglass) and remains stuck like that, with the game’s music playing in the background, until I end the task.
The global version acts somewhat differently. The game shows no graphics (black screen) even though its music plays. Opening the menu, I can move the mouse around, but it’s very jittery, and the black area where the game should have been playing graphics causes the mouse pointer to leave a looping trail wherever it goes. Once again, clicking anything permanently causes the game task to act like it’s frozen.
Hoping for suggestions.