My cruise requires a full moment of brake to cut out, the slightest fast tap is usually ignored by the system. The shifter has a solenoid just under the cluster that keeps you from taking it out of park unless it's powered up. I used to have some trouble with 4lo too, I found that putting it in neutral and bumping the steering wheel took off enough bind to go into 4lo quick and easy.

The brake would join all of these, but may not be the problem.