I just upgraded to Waves V12.7, and initially WL10 would not open any Waves plugins. I fixed it by rebooting and forcing full rescan of all plugins, now Waves work fine. This is on MacOS Catalina.
Reporting this in case anyone else experiences the issue.
Cubase Pro 11.0.1 |Wavelab 10.0.60 | MacOS 10.15.7 | 2019 iMac 5k | 64 GB RAM | Scarlett 18i20 interface | Waves V12.7