There's a simple explanation for this. The default setting is for stats from all opponent hands to show for all limits. Imagine a simple example: a player wins 1.5BB/100 at .25/.50 and loses 1BB/100 at .5/1. If the number of hands are equal for each limit then the BB/100 stat will be positive but with a net overall loss. A similar thing is happening here in your sample stats.
There's a simple explanation for this. The default setting is for stats from all opponent hands to show for all limits. Imagine a simple example: a player wins 1.5BB/100 at .25/.50 and loses 1BB/100 at .5/1. If the number of hands are equal for each limit then the BB/100 stat will be positive but with a net overall loss. A similar thing is happening here in your sample stats.