Solution in this post, but I believe that causes another issue!
Also with the same problem.....
I don't believe it causing any other issue. It's just half solution as it haven't impact to the list view.
BTW - I have thought about some possible alternate approaches to the data merging but no idea would it be implementable... Something like data merging exceptions in group settings. By default all groups are merged down but one repeated group (only one) could be not merged. In other columns outside this group "rowspan=#" would be used, where # is the number of repeats in nonmerged group.
see here for more discussion
Hugh has kindly fixed this :)