Can’t center the background with widescreen. Also, can’t move my character far enough left to center her inside the background.
It gets worse: Even if you do center the character with the portrait, the actual rendering is off center. You would have to use the portrait snapshot feature as a reference to help align your character. I find I have to move my character a few inches to the left and one inch down in order to get it where I’d want it on the portrait background. Complete and total mismatch. Clearing cache doesn’t resolve the bug I describe, but it might resolve yours.
ESC > Reset Settings > Clear Cache
Yeah, that’s janky. File a bug report to make sure they know about the problem. In the meantime, the workaround would be to temporarily switch to windowed mode and a resolution with 16x9 aspect ratio.