I've just tried trackr again and it is working a treat with the new update. Maybe Apple maps has sorted itself out a bit. I can't find another app that works as well and as simply as this one so it is great to find it working again on my iPhone5...
I'm really surprised that another tracking app doesn't offer the simple features this app has. Maybe MotionX GPS should offer to take over development of this app.
Just my 2 cents worth.