What do you guys think? Should your techniques work even when someone gets super rigid and muscled up?
You're using your shoulders and arms too much. Stop focusing on technique and sort your body out. Your arms should be just two ropes that are moved by your hips and spine.
If someone can lock down your technique it means you have a noisy body that gives off too many signals. Of course if you have a quiet body then you don't need technique you just throw them on the floor and there isn't much they can do about it and in fact the more they try to do something the more amusing it gets for you.
Hence "there are no techniques in Aikido" you learn the body skills, shut your body up and throw them on the floor as you please.