Render In Place muting old audio regions

Cubase
1

Hi,

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?

2

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

3

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?