I’m using Cubase Pro 10.0.20 Build 187 - Built on March 21 2019 on Mac OS X 10.11.6.
I just noticed some odd behaviour using the Mix6To2 plugin.
I had set up a 5.0 group channel and inserted the Mix6To2 to send audio to a stereo bus.
When I selected the preset for 5.0 to 2.0 mixdown the surround faders didn’t set to the correct levels.
Similarly for the LRCS and 5.1 settings.
See attached screenshots:
Easy enough to adjust manually, just unexpected.