I too use that vertical line for pinch hitters as well as substitutions. I would say that this isn't a high-demand update, but it would be a useful one that at least two users would like.

shot in the dark. export your data (options > export) and then delete the app and re install it from the app store.. this may help. (free from apple, if you use the same apple id you used to purchase it originally, it won't look free to start, but before it finishes the purchase it will say free) y...