Question about creating control knobs on the synth rack

The X2 manual says that to create control knobs on the synth rack, you enable the Assign Controls button in the synth strip, click on each control in the synth's property page that you want to create a knob for, and then turn the Assign Controls button off. The controls should then appear in the control strip underneath the synth in the rack (provided the control strip has been made visible with the Show/Hide Assigned Controls button. 
 
However I find that whether or not this works on a particular synth is hit and miss. For example, it works perfectly in Z3TA+2 and Kontakt. But if I try it with Reaktor, it just doesn't work. Nor does it work with Battery despite most of it's controls being automatable. Why is this? 
 
Another oddity is that when I try this with Z3TA+2, a double click is required on controls in order to select them for automation. For Kontakt, I just need to click the control once. 
 
Now I know that ultimately I can just right click on the control strip and select the automation parameter for a control knob from the menu, but sometimes this is a pain especially if the parameters are poorly organized and labelled and generally hard to find. Being able to click in on the synth itself is a major convenience, and I just wish it worked for all synths - unless someone can tell me I'm doing something wrong here.