This is apparently a problem with newer iLok plugins – i.e. those built with the latest iLok development kit. cf. Cubase 14 Pro hang on VST3 scan, Windows 11 - #9 by rickpaul
Killing the vstscanner proces - NOT the vstscannermaster proces - allows the scanning to proceed with the offending plugin blacklisted. You may have to repeat the proces for every offending plugin.