Resetting security for External Plug In

I downloaded a dmg file that contains a component file for a guitar amp simulator for Garageband. It did not contain an authentication certificate, so my Mac "ignored" the file after alerting me to the fact that it was not secure. I know now that I should have opened Security and Privacy settings to allow the plugin (it is legitimate, and does not pose a risk), but I failed to do so.

Now, I can't get Garageband to even see the component file. I have deleted and re-added the component file. I have added the same component file with a changed name, I have re-installed Garageband, and I have reinstalled Catalina. I even reset all permissions through the repair portal. None of these measures has caused the security to stop ignoring this component.

Is there a way to reset the security protocol for this file, so that I can have the option of allowing it again, through privacy and security?