Problem appears to be resolved: Uninstall the WIBU key driver and re-install from the Graphisoft website (version 6.20).
For info: we had uninstalled the WIBU key driver and installed the latest version (6.30) from the WIBU website, but the problem persisted.
Many thanks to Graphisoft for their extremely rapid support.
AC28. Twinmotion.
16" M1 Max MacBook Pro 32GB, Apple Studio Display, MacOS 15 Sequoia