This is perplexing; it may be worth letting PGMusic support take a look at it, or whoever else you trust. Is Live Chat available at the top right of this screen?

It sure does sound like a setting in RB is the cause (since everything else works as expected), but I can't think of what it would be.
There is a MONO checkbox in the RB Mixer screen, this couldn't be it, could it?

Have you tried renaming the files Realband.INI and RB.CFG?
If you close RB, rename those files, then re-open RB, it will reset your RB settings for devices (essentially a factory reset).
It will then recreate those files as it launches.
Should things actually seem worse after trying this, you can rename those two files back to their original name to get back to where you are now.

Both of those files are in your active RB folder (usually C:\Realband)






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