Mix and render to new track

Hi have always mixed mono vocal with stereo backing track using mix and render to new track no problems but suddenly what happens is it creates the new track but the vocal an backing are separate

Hmm, it seems to work for me.
What exactly do you mean: “but the vocal an backing are separate”
(perhaps it would be helpful to post a couple of screenshots, one before and one after “Mix and Render to New Track”).

Aye has worked for me for years what is happening is mix and render to new track using one vocal track = 1channel and one backing track
=2 channels this normally creates a 2 channel track with the vocal mixed . Now I get 2channels with the backing on one channel and the vocal on the other

Which exact version of Audacity are you using? (look in “Help menu > About Audacity”.)

3.0.2 and it has not done it before and does not happen on any other projects

Thanks for your interest now sorted not quite sure how but it OK now I