On Win 7 Ultimate Ultimate x64, Lightroom 3.6 x64, LRTimelapse 1.6, Exiftool 8.7.7.0 in program directory. Project used Canon *.CR2 files from 7D.

Learning the workflow. Wanted to start a project over. In Lightroom, selected Photo | Develop Settings | Reset (Ctrl+Shift+R). Closed app. Cleared all *.xmp files from directory.

Started LRTimelapse. Selected project directory. Yes, to LRTimelapse to create metadata, save, etc., the viewer display shows the message "Dimensions Unknown". The data table shows no value for Width and Height information.

Back in Lightroom, In Library under Metadata, the dimensions are present. Ctrl+S in Lightroom, then Reload in LRTimelapse does not change anything. Where does LRTimelapse get it's dimension info from?

Your workflow is correct!
Unfortunately LRTimelapse can't show the dimensions in every case. But anyway that doesn't matter. They are not needed for other things than information.
Best
Gunther