Is it your code that link with IPP, or is the vendor code linked with Intel IPP?
The application is 64 bit, it needs to use mx libraries (or other optimized 64 bit libraries), px library does not work there. If IPP linked within your application, it is fine to relink 64 bit IPP with your code, but IPP is already linked in the vendor DLLs, it need the DLLs to relink with the 64 bit IPP library.
Thanks for the update. Just in case, please take a look at an article about different IPP error messages.
I hope that it will be useful: