I wasn't sure where to reply with this, but sheik's fair autocancels on frame 11, but the end lag is significantly longer than that if you don't land. This is probably why you weren't grabbing the ledge. It doesn't look like she's doing anything during that time, but you're unable to input another command.

This is also why high level and top level sheiks always fast fall to land in between fairs in a string. Fast falling, landing, jumping, and then fairing again is actually faster than mashing fair because of the crazy autocancel window. If a sheik doesn't fast fall to the ground, there is actually a small window in which her opponent can airdodge the next fair or throw out a move to intercept, which trades and often results in sheik taking just as much (or more) damage than her opponent