Audio Mixer Exposing Aux Sends causing issues on multiple computers

I'm hoping to see if others have this issue or could test if the same problem occurs on your end. It's become a roadblock for my app. In a nutshell, Exposing 'send levels' seems to be buggy.

On a group in the Audio Mixer, I create a send, and assign this send to a receive on a second group. Then I Expose the send level, and can see it listed in the Exposed Parameters as 'MyExposedParam Send (of Track 1) - which is good. But once I enter Play mode, the Exposed Parameter changes to 'MyExposedParam Send (of Master)' - which is the problem. The problem means it's not possible to control the send level on group 1 from code. I need to expose around a dozen sends on different groups via code, and the issue occurs each time.

I've run into an issue on 3 computers (PC and Mac using different Unity versions) and for each, I've started a new blank project to test this problem. I've tested 2021.1.0b1, 2019.2, 2019.3 and 2020.2.

The strange thing is this problem didn't use to occur. My older projects with sends exposed still load in Unity, however, in the Exposed Parameter list they now say 'MyExposedParam Error Finding Parameter Path'. These work as they used to even with the error message, however, I'm unable to expose new send levels as they revert to the 'MyExposedParam (of Master)'.

Any help testing this on your computer would be most appreciated.