Submit same file twice get different results

Not sure if here is the right place to post this message. 

I have a c++ program build with Visual Studio 2017.  I uploaded the exe file to security intelligence, and got "No malware detected" for both client and cloud protection, but after  a while when I clicked the "Rescan Submission" button, it instantly showed "Program:Win32/Wacapew.C!ml "  under cloud protection.  

The strange thing is, I uploaded the same file again as developer, it finally showed "No malware detected" after period of time waiting. 

How could this happen, same file got different results, really frustrating.