Render in place wasn’t working for me at first, but I figured out if you go to render settings, select “As One Event”, “Complete Signal Path” and “Mix Down to One Track” it will convert the two mono tracks to a stereo one. I hope that is helpful to someone.
The disadvantage is you have to choose a name for the file. Since I’m converting many different file I gave it a generic name like “Rendered” and it will automatically increment (Rendered-01, Rendered-02 etc)
A good feature request would be the ability to type %NAME, so the rendered file would be automatically set to the name of the mono tracks you are converting. Or simply add the feature from Nuendo into Cubase. A lot of times I have extra audio besides what’s in the event (handles you can extend) and the RIP process destroys the handles. So the Nuendo process is probably superior if it is able to render the entire file and not just the part of the event that is being used.