Yes, the On One tugs aren’t long enough for all gear ratios. I’m now running 34/17 and it was *just* fine when the chain was new, but has now stretched slightly, and the chain comes off with the screws done up tightly. Taking out a link made the chain too short, so I have one half link which I add to my 8 speed chain to get it to an acceptable length. Once it stretches a bit more, I’ll take the half link back out. Had to do the same when I was running 32/13 too.
I find I’m fettling with the tension quite often. I think the chainline is straight, and the skewer is not bent, but I’m now wondering if the axle is damaged, as the chain tension doesn’t seem to be even. Most annoying.
Long story short – you might need one half link (available from velo solo) or a half link chain.