Calling a mex file from matlab compiled shared lib (.so)

I create a Matlab shared lib (.so on a Linux system). Part of that build is a mex (.mexa64) build for fast median calculation. Using -a with mcc, I include the mexa64 file in the libXXX.so and send it to the target system. The C++ application sends data to the Matlab shared lib and everything works.

New requirement: parallelize fast median mex with openMP pragmas and dynamically set the number of threads to use for computation based on the resources of the target system. In other words, the mex file needs to be compiled on the target system for the libXXX.so to use.

Easy enough to compile mex on target system with the only MCR installed. Everything good so far.

Then the dreaded Cannot locate XXX.mexa64.auth file. Apparently the only time the auth file is made is when the mex file is extracted from the CTF.

Is there a way around this auth file. I don't need authorization to use the .so on the target system, why for the mex? And more importantly, how do I make this work?

Adam