Lightworks detects aspect ratio incorrectly and clips video from ShadowPlay
No clue about Lightworks, but two possible (and possibly related) issues are that 1366x768 is not exactly 16:9, and 1366 is not evenly divisible by 8. Either or both could cause any editing software to use a different internal representation, and require an adjustment to its display.

1368x768 would be byte-aligned, but still not 16:9.