Acrobat Reader (custom) Plugin for Mac version not loading

Updated an older plugin to 64bit for latest MacOS but it won't load.

The 64bit version was necessary to support the gatekeeper requirements during installation of the plugin but got side-tracked since the new plugin itself fails to load now. The previous 32bit version loads ok on the same OS and Reader DC version.

Any pointers to resources on proper 64bit plugin build requirements for the Mac version of Reader on Catalina+ OS versions?

PS: Yes, the plugin is signed for Reader