Right-click the audio event, choose "Channels" and the "Left Only". That will play the left side on both sides.

Set track to mono.

When only one channel (left or right) is selected (as was previously stated), the vent is automatically changed to center panned mono (unless the Magix 'deep-thinkers' changed it in VP-17 or 18).

@rraud I am on Vegas Edit 16 and all the audio shows on the left channel only. The Tascam DR-60 MK II seems to have complications. I have a shotgun mic on mono for XLR input line one and on channel 3/4 had the stereo input from the lav mic. (Line two is an XLR port for another mono signal). I am not sure if the unit can accept mixed signals.

Put your mono track on the timeline. Do a Jetdv says. Put your stereo 3/4 track on the timeline. Mix to suit. Render to stereo.

Another option; In VP's "Options> Preferences> General", there is a setting to import stereo files as dual mono. This will give your two 'separate' mono tracks on the timeline, instead of a two-channel stereo track, you could just remove the track you do not want or mix them separately.. if for instance, a boom mic is on channel-1 and a lav on channel-2.
Assuming the DR-60 tracks 1 & 2 are an interleaved stereo file, which I believe it is, Tracks 3/4 and 5/6 would import as dual mono as well for total of six mono tracks.

@rraud

Sorry for the late response, another time-sensitive project slammed my way. There is good news and bad news. First good news, I spoke with Tascam about the DR 60 MK II and they said I need an XLR-splitter cable to record the way I need to. The device cannot mix a mono (shotgun) and stereo signal (lav), but if the shotgun is split, I can get four channel recording. I tried this on the last client and the audio was MUCH better.

Bad news now, I have awful audio for this shoot. The reference audio for the camera (audio with video) is distorted and the audio on the SD card from the DR 60 is too low. Also, all audio is left channel only. May I post the (better) audio samples somewhere for you to assess whether it is salvageable or that I must go back and re-shoot? Where can I post?

"Where can I post?"

Dropbox, OneDrive, GoogleDrive, pCloud, Mega, ect, ect. Most give you a 15GB free account, except for DB which only gives 2.5 GB (free, as I recall.. but DB sucks in other ways as well IMO). If you have a Gmail email address, then you have a Google Drive account already. Same with Microsoft's Hotmail or Outlook email (you get OneDrive),

@rraud

Sorry for the late response, another time-sensitive project slammed my way. There is good news and bad news. First good news, I spoke with Tascam about the DR 60 MK II and they said I need an XLR-splitter cable to record the way I need to. The device cannot mix a mono (shotgun) and stereo signal (lav), but if the shotgun is split, I can get four channel recording. I tried this on the last client and the audio was MUCH better.

Bad news now, I have awful audio for this shoot. The reference audio for the camera (audio with video) is distorted and the audio on the SD card from the DR 60 is too low. Also, all audio is left channel only. May I post the (better) audio samples somewhere for you to assess whether it is salvageable or that I must go back and re-shoot? Where can I post?

Not sure what you were attempting to do. I have recorded both shotgun and lav mic into DR 60 MkII (in my case via a Sound Devices Mixpre-D), one to each channel, no problem. No need for a splitter. I have not heard of a stereo lav, I think most if not all lavs are mono.

@rraud Thank you so much, I was more referring to whether there is a preferred service to use with Vegas Forum. Here is a link: https://fil.email/iqt4LzAx

Not a good recording, the extraneous (din) noise can be attenuated 25dB so w/o annoying artifacts but the voice quality ain't there to begin with. I would re-record it if that is an option, If not, it 'may' be usable with tools that are available within Sound Forge if you have it. The below link is a demo, which took about 5 mins to do in SF Pro. A better result is possible with more time and RX Advanced and/or Spectraulayers, but RX Elements attenuated the din noise decently. A hi & low pass filter and expander helped a little additionally.

https://u.pcloud.link/publink/show?code=XZg2MJXZUAoEktEctyBrshgkGp7z9XpVkpIy=====

@rraud Thank you so much. It is best if I go back and re-record. I do have access to audio repair DAW's, but nothing can beat good, clean audio and now I know I can do it. I just hope the client is not too angry...