CryptDecrypt result is table of NULL on Windows 8, on Windows 7 not

Question

I am trying to decrypt a RSA encrypted string using CryptApi function CryptDecrypt. Code works on Windows 7 64, but on Windows 8.1 64 CryptDecrypt in decrypted buffer returns table of \0 characters. There is no error, CryptDecrypt does not return 0, GetLastError() is 0.

I tried using different CSP available in Windows, but it didn't change anything.

Does anyone can explain to me this behaviour?