no, the problem was setting the compiling target to use 'ANY CPU' this means that running on 32-bit everything will run in 32-bit, and on 64-bit the runtime will try to execute it as 64-bit code even if it was meant to be 32-bit.

So I force the code to compile as x86 ensuring that running code on 64-bit runs it in 32-bit more and doesn't try to 'upgrade' it to 64-bit.

It's just something I forgot about, lol, but didn't have a 64-bit machine to test so I asked my friend.