When a secondary site node "leaves" the cluster by selecting leave the cluster, there is an error messages ( simply "error") displayed. After clicking the x and returning to the GUI screen it does appear that the service has now been restored and the process is complete.
The problem here is that it can cause a additional problems if you do not wait further and allow the rest of the process to complete.
Release : 3.4.2
A problem occurs because the process of removing the node has not really completed and even restarting the node without waiting can cause the process not to complete on the rest of the cluster.
This node may leave the cluster in a state where no further changes can be made to the cluster without restarting the cluster or having a support engineer log into each node and clear temporary files.
This has been addressed in later versions but does require some additional documentation in the support system