We strongly advise users to not upgrade to macOS 10.13 High Sierra as yet.
We’ve recently discovered an issue, that BIMcloud or BIM Server will prevent proper shutdown/restart of a computer running macOS 10.13 High Sierra. Instead of properly shutting down, a computer will display a spinning wheel or black screen indefinitely.
Please consult our Help Center article for a discussion of the issue and its workaround.
This specific problem will be addressed in the next updates for both v20 and v21.