Brand new Digitone 2.
In FM Tone, Algorithm 3 changing the B Volume doesn’t change the sound no matter what other parameters are changing as seen in the video linked on the reddit post.
That is due to the nature of algorithm 3. If you look at the algorithm map, you will see that neither of the B operators is modulating any of the other operators, they are both modulated by operator A, and the volume is controlled with the “mix” parameter, with the mix fully at “X” you will hear a mix of operator C and operator B2, and with the mix fully at “Y” you will hear operator B1.
When you adjust the level control you hear no change on the sound because that control is not the volume of the operator, it is the modulation depth of it on any other operators it is modulating. So on this algorithm, since the B operators aren’t modulating anything, that level control will have no effect.