Version 12.0 included an embedded workflow indicator (bookmark type fold in upper right of a workflow monitor), this no longer exists in 12.3:
Add a second workflow within the workflow.
Click Last Monitor
In the workflow monitor, there is no Embedded Workflow indicator to click on.
Double clicking on workflow expands it instead.
Release : 12.3
Component : AUTOMIC WEB INTERFACE
In 12.3, Double clicking on workflow expands it instead.
There are currently no plans to re-introduce the Embedded Workflow indicator as the change has been identified to be too large for a bugfix.
If the re-introduction of this feature interests you, please file an enhancement request.