My sidi dominators soles work great with my frog cleats, but I have found other bike shoes soles seem to kick the cleat out. I have cut the soles' lugs down a bit around the cleat and that does seem to help. Some of my bike shoes I've given up on wearing for fear of coming unclipped.

Older cleats will unclip too soon so I have to replace mine more often than I'd like. It sounds like yours haven't had much wear so that probably isn't your problem.

I hope you can get it figured out. The spds don't like my knees either.