Playback from left output only

One project file I am working on is being showing recurrent playback misbehaviour. At first and apparently out of the blue, only one instrument was sounding in playback; issue was solved by reloading the playback template (HSS+HSO pro). Now playback is only coming through the left output, despite all balance and pan controls being set to the centre. This happens only with one specific file and with any output device I have tried (I suspected my headphones were broken, but they aren’t). When triggering the balance or the pan controls to the right, sound fades out.

Thanks in advance for helping!

Very occasionally somebody will report that playback only comes through either the left or right channel, but I don’t think there’s a single known cause for this. Does the problem affect all projects, or only this one? If the problem affects only this one project, can you zip it up and attach it here?

It does happen only with one project (fortunately). That’s why I’ve being trying to figure out if I touched any internal parameters before addressing the forum.
The only thing that comes to mind concerning playback, though, is that what could have happened is that I might have used a Bluetooth speaker as output from Preferences>Play>Audio Device Setup and then disconnected or turned off the speaker without changing that setup first… I don’t know if there might be a possibility of that having corrupted the file?

Anyhow, thanks for you help and advice.
I tried attaching a zipped copy of the project, but the file size is still too big (2.4MB, same as the original .dorico). Should I send it to you by other means?

P.S. While writing, I exported the .wav audio file of the project; I hear it correctly through both outputs.

Or send it to me: u dot stoermer at steinberg dot de

Done! Thank you!

Update:

Problem solved by copy-pasting my score to a new project. Playback is now performing correctly in the new project/flow.
Issue persists in the old (original) document; file corrupted?

Thank you all for the feedback and help :wink: