The problem I had was that there was (is) a twist in my bungee which cause the slack sprocket (on the s-hook) to be a bit rotated. I could take the bungee off of the s-hook/sprocket and try to untwist it, but then the sprocket would just end up rotated in the opposite direction. This problem was the worst when there was less slack chain (the the bungee near it’s most tensioned) because the s-hook sprocket was closest to the motor sprocket. Because that s-hook sprocket is still rotated and there’s not enough distance between it and the motor sprocket, so that misalignment caused the chain to skip.
I also had some chain sticking problems but that’s mostly fixed now by switching to a weight tensioning system instead of bungees (though the slack-sprocket-rotation issue still happens without these chain guides).