Engineers have completed maintenance on the affected database clusters and services have been restored.
A backup process on the host node caused the instances to lock up - so our team will investigate changes to the backup regime and timing to avoid any further interruption.
Our data center have advised us of an issue impacting parts of one database cluster in our US data center that is causing some simPRO users to lose access to their simPRO system. They are currently working to rectify this issue as quickly as possible.