It never occured to me to use Cut video + Perfect loop. You are correct, it will not work if you are using Cut Video, for now you need to disable this option for Perfect loop to work.
"Perfect loop" will create the number of frames that you set as a output.
2X = 1 new frame to close the loop
4X = 3 new frames to close the loop
8X = 7 new frames to close the loop
You can also export as a PNG and delete the frames you don't want