Yes, the game runs at the same resolution regardless of where I place the window or start running the application, however, I decided to go deeper with your new message, and I disabled all the videos and ran the game again. Result: both 60hz monitors ran the application at 60 frames, the 75hz monitor ran at 37.5 frames.
I forced monitor 75 to 60, and again, framerate was stable. In the same case, I let the game run at unlimited maximum frame rate, but again, stable at 60fps. In that case is it the counter that doesn't work or the game really doesn't pass 60fps?
EDIT: Additionally, with the 3 monitors active, game in 60fps max, I left monitor 1 at 50hz (1080p, not the main one, just port 1). I ran the game from monitor 2 (1440p, 60hz, main) and the game ran at 50fps. In this case another monitor influenced the total frame count.
This story becomes more intriguing though, at least my case of lag was "resolved". Perhaps a background update from Nvidia was what started the problem over here? (even at 75hz the game ran normally before)
This also doesn't solve your lag case and other people's, but I certainly already have a point to keep an eye on and question about.
I wasn't prepared to think so far out of the box, maybe the next step would be to use a multimeter to measure the alternating current of the residential electrical network? haha