Incorrect file header for mono files copied from stereo file.

When a single track is copied from a stereo file (L or R) to a new file (Edit > Copy To New) and saved, the file header probably still says it is a stereo file. I though this bug was gone but it looks like it isn't.

When sending to Izotope RX6 for example, RX6 receives a stereo file (with only audio in 1 track). This also happens when unchecking "save metadata" and when closing and re-opening both audition and the file. Pro Tools also used to think it was a stereo file. Build 11.0.2.2