I can't seem to find any timecode that reports back the CT while doing a RAM preview. Am I correct in assuming this does not exist?
As a workaround I added a solid layer and added the timecode effect to it. Seems weird there is no playback timecode reported in any windows during a RAM preview so I must be missing something.
To get a display of timecode in the comp window that's what you need to do. The time indicator in the timeline does not advance in a ram preview. The info palette only shows the fps if enabled.
The timecode effect applied to another layer or an expression from the expression library for timecode applied to an empty text layer will do the trick.