There's better places to fish than dike 3, considering how pressured it gets.
Also Try Swiss cheesing the ice and drilling multiple holes all over the humps. Chances are they were probably on the move swimming up and down the humps looking for food. My technique that I like using on granby that tends to work for me... is finding the top of the humps with my vex, and if it doesn't produce in 10 mins, going back 7 feet deeper and repeat process. More often than not, eventually i find steady action. Changing baits and downsizing works too.
I'm here to ruin it for ya,... I, spoiler.