More specifically, ID3D12GraphicsCommandList calls submitted with ID3D12CommandQueue::ExecuteCommandLists can be viewed in this trace. It is important to note that not all ID3D12GraphicsCommandList calls are displayed within the GPU Trace window. At the moment, only a subset of API calls are collected:
The timeline shown within the GPU Trace can be thought of as a sampling of command execution on the GPU. CommandLists are built on CPU threads by invoking calls to ID3D12GraphicsCommandList, and then one (or many) CommandLists are submitted to the GPU within a ID3D12CommandQueue during the ExecuteCommandLists call. The results of the GPU Trace intend to show the GPU execution density over time for the current frame. Each command that was executed is given an item in the timeline, where the width of each item corresponds to the total execution duration on the GPU. To find the exact execution duration info for each item in the trace, hovering over each Command in the timeline will open a tooltip including start/end timestamps.
Note: This feature will only work when using the "Linked" trace mode. Finding related calls in a separate trace tool requires all trace data to be populated from the same original frame, which is what the Linked trace accomplishes. Read more about the Linked Trace here.