I think it´s the raised sights. If the barrel is to long, the pistol shouldn`t snap into place.
I have to Micro Roni for Glocks. Gen 3 and Gen 4 Micro Roni. On the Gen 4 the internal muzzle of the Roni can be extended out a bit, so larger Glocks can be fitted into the Roni.
For that, there is a setscrew on the top of the muzzle on the Roni. If this also applies to the Micro Roni for the CZ P07, I don`t know. They mdae this option for the Glock plattform, so upto six Glocks can fit the Roni.
On the CZ there is only one CZ P07 modell. Only difference would be with or without threaded barrel and in the case of threaded barrel the higher sights.