I'm only beginning to look at this...
Did something knowingly change with loading plugins on macos betweew 2.9.0 and 3.0.0? When I build a plugin with the 2.9.0 source tree, I can copy the plugin to a system with 2.9.0 installed from the official installer and it works. If I build the same plugin with the 3.0.0 source, and copy to a system with 3.0.0 installed from the official installer I get an error complaining about the code not being signed.
"not valid for use in process: mapped file has no cdhash, completely unsigned? Code has to be at least ad-hoc signed."
So far quick searching hasn't turned up an obvious explanation that the code needs to be handled differently.
Jason
