Someone at AVSIM suggested that MSFS has a bug that renders your FPS at half the refresh rate value. So if you set vsync for 60, it will actually work at 30. The solution is to turn vsync off in game, and use the vsync settings in Nvidia control panel. I will try that later. It’s very possible that I’ve somehow triggered this bug in the last few days.
Ps. I think your understanding of how vsync works is off. I’m no expert, but I can tell you what I see in my games…
I run a 3090 on a 4K monitor and all my games I’ve set to max image quality, which means I tend to get frame rates around 50-80fps. When I turn vsync on, I get 50-60fps as vsync will cap the upper limit to my display refresh rate. When I turn vsync off, my FPS will fluctuate between 50-80. In NONE of these games, will I ever see 30fps… except MSFS.
My normal FPS in MSFS is around 40fps. Prior to a few days ago, with vsync on, I was getting 40fps but now I get 30fps. Something strange is going on with MSFS.