Half link chain on fixed gear; Smooth one way but notchy/jumpy the opposite way?

I’m running a half link chain on the Fixpedition and an eagle eyed member correctly pointed out that I had it on backwards: https://www.reddit.com/r/xbiking/comments/1qz0q4z/comment/o4au0hz/

I rotated the chain around (to run the rounded part forward) and quite surprisingly, it was worse. Like, a lot worse: generally noisy, and 'notchy' or jumpy at a couple of points through the full rotation.

I tried quite a few things: slightly different wheel alignment/centering, different chain tension, rotating the rear cog, re-lubing the chain etc. No dice; still notchy.

This older thread describes pretty much exactly what’s happening when the chain is the correct way around: https://www.reddit.com/r/bmx/comments/hkr70r/is_this_on_the_right_way_bsd_half_link_is_making/

I’ve since rotated the chain back to how it was (rounded part rearward) at lo and behold – it is fine.

However, it’s now notchy when backpedalling – have a look at the above video to see & hear what’s happening (sound on).

What’s the go here? Obviously the half link chain link shape is asymmetrical, as opposed to the symmetrical links of a full link chain.
Does this somehow affect the chain/tooth interface in a way that makes it worse in one direction compared to the other?