Garageband no longer recognizing my iLok plug ins

I've been using both slate digital and soundtoys plugins through iLok license manager in garageband successfully for a while, however after an OS issue which required taking my macbook to a recognised support technician and getting the OS re-installed to the latest update (Monterey), which included updating garageband, the same plugins are no longer recognised. If I try to open a project file that had previously used a plugin, on start up I get the errors:

• "NSCreateObjectFileImageFromMemory-zgz0ooa8" cannot be opened because the developer cannot be verified
• Fatal error: 100001
• Audio Unit plug-in can't be used.

I also get similar errors when opening a new project file and trying to add the plugins. The plugins still show up in the smart controls UI of garageband, but just don't work and give errors when I try to add them.

Ive tried removing the cache files for the plugins and also tried completely uninstalling and re-installing both iLok license manager and all the plugins. Would appreciate any help.