AppCode Extract Function Issues

Question

I'm a student and have obtained a year free subscription to AppCode (via their student policies). I downloaded it to use it in conjunction with Xcode, to refactor C++ code. I'm noticing issues with the extract function feature. I've tried it a handful of times, but I almost always get errors. My initial thought was that it would automatically recognize that the selected code has variables, and introduce them in the function as parameters, but this didn't happen. I have to manually enter them in, or else the function is inserted and errors occur. After a handful of attempts, I had one situation where it DID recognize variables and created the function perfectly, entirely on its own. Does anyone have any experience with AppCode and have any information on why it seems to randomly extract functions correctly only on a rare occasion without any help? I dont entirely mind doing it manually, but at that point, it sort of defeats the purpose of even having a function extraction tool, as I can just do it all manually.