For starters, in the context of PP, mono will always come out both speakers, unless something is wrong with that speaker or you have it panned to one side. Having sound come out only one speaker doesn't necessarily make it 'mono', it just means you're only hearing one side of a stereo pair, or you have it panned to that side.
The reason I point this out is because I'm a little confused. Are you actually working with genuine mono tracks, or stereo tracks? Are the clips in that track really mono, or stereo with different audio on each side?
Thanks for getting back to me Jim.
This is what the properties tab of the audio clip says:
Type: Windows WAVE audio file
File Size: 5.3 MB
Source Audio Format: 48000 Hz - 24 bit - Mono
Project Audio Format: 48000 Hz - 32 bit floating point - Mono
Total Duration: 00:00:38:14211
I had assumed the audio was two mono tracks.
I may not have explained myself perfectly.
I can hear the audio out of whichever solo channel I select, but not both channels at the same time (eg in my bars and tone experiment, I can switch between channels and here tone in either, but not both simultaneously). My deduction from this is that the sound card, speakers and headphones are ok. I've listened to music etc through my headphones and know also that stereo is working ok.
Previously I could hear both channels simultaneously. Whilst I could carry on as it currently is, I would only be able to hear the audio out of one speaker/headphone. Plus I also want to know what has changed since I started the project and it was working ok.
Could it be a problem with a codec? Or an issue with upgrading to win 8.1? My sound card is a Creative Technologies Sound Blaster X-fi Xtreme Audio card.
Thanks for you help
To answer my own question, I had installed Nuance NaturallySpeaking which installed another codec that, for whatever reason, changed my speaker settings from stereo to dolby 7.1 surround sound.
I went to control panel > sound > speakers > right click > configure > stereo.
Hope this helps others.