Well you say it is uke's job to stay connected. Maybe, maybe not. Sure, at a beginner level...uke probably should try and stay connected.

At a higher level though, uke is never wrong.

Uke stays connected because if he/she does not...bad things are going to happen and he/she instinctively figures this out.

If he/she does not feel this then one or two things are going on.

1. Uke is oblivous to the fact that you can make things worse for him.

2. You are creating conditions in which uke really has no "incentive" to hold on.

Speed typically makes things worse as either one or the other of you is in a different part of the process and it doesn't work out for you and you have to do something else.

Go slow when working on this aspect.