What’s the deal?

Often when attacking in pvp match, as soon as I destroy a building that will bring me over the 70% victory threshold the game crashes. It never happens when I’m less than 70% or over. Only happens when I hit 70%. Then it counts as a defeat. What is the hack?

Also, even when attacking lvl 59-64 I still don’t get rewards any better then criticals for units I’ve already maxed such as reapers, abrams and matching gunners. Or helicopter commons. How do I get a criticals for units I actually use?