FYI, anyone who runs into this problem, it seems that this is now fixed in the unstable version.
I had the same issue when running Dynare++ (from the 4.4.3 release) on macOS Sierra.
Installing the unstable version of Dynare (and the Dynare++ that comes with it) resolved the problem without having to mess with the libBLAS.dylib file. So while waiting for the new stable release of Dynare, try installing the unstable version and use that when running Dynare++, even if you keep the old stable version for regular Dynare. See here for installation instructions: Unstable Mac Version of Dynare