Render In Place muting old audio regions


I’ve just used the Render in Place option on Cubase 10.5.

My old audio regions are still in place but will not sound now. Why is this?

I should point out that I have selected ‘Keep Source Tracks Unchanged’, whilst rendering but still it’s muting the old regions.

I’ve just discovered that the muting only occurs if I try to process a number of tracks at the same time. If I process individual tracks then it does not mute the original source.

What is causing this inconsistency?