If have just released a new version of Leaf Spy Lite. It is a small update so is still v0.27.
It allows the selection of "Secure" connection instead of the default of "Insecure". The difference being that for Insecure you need to supply a port number (default is Port 1) whereas with Secure you do not.
If you have trouble connecting with the default setting of "Port 1" then try going to the last entry in Port selection (Settings/System panel). It will be the last choice after "Port 30" at the bottom. Exit app then restart and see if that helps.
I would be interested to know if for those that had to select Port 16 if this option also works for them.
For now it is only available in Leaf Spy Lite but if I hear positive reports that it works in some cases I will add to the other versions of Leaf Spy.
I know for a fact that "Secure" does not work on the Nexus 7 which I have and is the reason I switched to the "Insecure" version with port number.
You may get a request for the pairing code the first time you use "Secure".