Seek time giving different frames

[Angrod90]

I don't really know what title would be appropriate, I hope this will be ok.

I have a few videos (very similar) compiled with ffmpeg.exe -y -framerate 30 -i "MASTER_%04d.png" -c:v libx264 -x264opts "keyint=5:min-keyint=5:scenecut=-1" -crf 17 -pix_fmt yuv420p output.mp4. I play them flawlessly with vlc but, when I go to some specific times, the two videos are in different positions.

I want to put them on the same time and then with alt+tab compare them. When i go to the fourth second for video A takes me to the I keyframe and for video B takes me to I+1 keyframe, but if I go to the third second all works fine, I tried to compile them with every frame a key frame and then I've got no trouble but that is not an available option (they weight too much) for the everyday use.