The "Use strict volume identification" setting has always been disabled when the destination lacks a unique identifier (because the setting isn't applicable in that case). Now we also uncheck that box in those cases to avoid any confusion about whether that setting will be applied.
Minor adjustments to the timing of snapshot creation on the source at the beginning of the task. These accommodate archiving of the source volume's helper partitions and also resolve potential conflicts when several tasks are started simultaneously that use the same source volume.
The postflight destination unmount subtask is no longer skipped when a task is aborted due to a time limit overrun.
Fixed an issue related to manually mounting an encrypted source or destination volume (when clicking on the source/destination selector).
Fixed a cosmetic issue in which custom filters with multiple suffixes (e.g. '*.tar.gz') would appear to not be applied to matching files in the Task Filter window, despite actually matching those files during task run time.
(CCC 5.1 release notes/new features are in April 27th news.)
More info on Carbon Copy Cloner 5 (including 30 day trial) at bombich.com.