Hi,
System trace is designed to help users understand upstream and down stream " points of interest" from the selected system start point. Points of interest vary per system type, but are generally pieces of equipment, start points, or endpoints. Currently trace is limited to standard Revit System Classes.
From the screen shots, there could be a few things going on:
1. The model isn't supported: Is this a hydroelectric dam? If yes, unfortunately Tandem doesn't officially support Civil projects and the Revit class configurations we have won’t work well for this use case.
2. "Diversion Outlet1” isn't connected to anything interesting: What are you trying to accomplish in trace mode? Perhaps we can extend our definition of "points of interest"
3. There's a bug in Tandem: if sometimes your seeing options to trace and sometimes not, please log a bug report with more information about what you are trying to do and how you produced the issue so we can look in to it further.
Lastly, System Trace works best with a cleanly connected system. Use "Refine System" (accessible from Systems panel per system) to clean up the subsystem connections. You can increase the “viewing connections” length to ensure that the start item and the end items are connected.