Single nut strut top mount jiggle

i was doing the front brakes on my daughters pain in the butt prius c, and noticed one of her front struts leaking oil and creaking and binding. so i popped in a pair of complete shock assemblies. these prius c have only one single top mount nut instead of the regular three top nuts. i don't like it. anyways, everything installed smoothly, new links, double checked everything i touched, tightened top nut under load (jack under lower ball joint) and here's my issue:

when i turn the steering wheel side to side (still up on jack stands, I'm waiting for more parts) i hear clicking. investigating this, if my hand is on the top nut i can feel the click and even see a wiggle. is this normal? i tried loosening the top nut, jacking back up, and retorque, same thing.

please if anyone has done this job and can advise, i would be very grateful!

 

so dropped the car on the ground to tighten top mount nut, same thing. just doesn't seem to be seating correctly when it's torqued down. but maybe this is normal? this is the first tiny hybrid car i have had the pleasure of working on, and there are many things that are similiar but different from regular cars.

 

This is under load,