It does work, that’s for sure. If you want to write out an exact step by step sequence of what you are doing, starting with no note expression data in the notes maybe we can help you understand what to expect.
Press the record button and change some exp data mid note.
Result: the expression data for the notes is rewritten so that the initial value is the value in which I started moving the midi controller.
Initial recording:
After overdubbing:
(The error is when I started overdbubbing)
The “Reset Latch buffer” stays disabled.
I expected the overdub to take effect only AFTER I started touching the control, leaving the note exp data before, untouched.
Unless I did not understand something about how it should work. You gif only showed the Reset Latch Buffer enabled, and how I’m not sure how you got to that state.
If the Latch Buffer is disabled and you start to record, the value of the CC jumps to the position at the moment, once you move the hardware controller. So within the note, you can see the jump from the old value to the new one.
If the Latch Buffer is enabled, the very first incoming MIDI CC value is extend to the very beginning of the MIDI Note (ex post, of course). So you don’t see this jump from the old value to the new one.
But here on my side (and I understand, you get the very same result), it seems like the Latch Buffer is always enabled, right? So you can’t get to the state, of the “jump” from the old (already written) value to the new one.
Moreover, if I try to record in the cycle, it seems, only the very first record is taken in account. I can hear the following records (incoming MIDI data change the sound), but they are not written/recorded.
I would say it’s a bug. Because it doesn’t matter if the Latch Buffer is enabled or not, it behaves always like as it is enabled. And from my point of view, this is the bug.
Btw, the very same behaviour is in Cubase 10.5.20.