Almost a year later I know, but I would be curious to see if the OP or other people had any more experience with this, or an answer to the OP’s question.
I have 12 outputs activated from Geist for snares, various percs etc. I was trying to get the high frequency percussion from two samples, lets just say Hats 1 and Hats 2, to make room for each other in unique ways. Hats 2 is a kind of reverse sample that builds slowly over a few bars from 5khz to a definitive 14khz peak that lasts a second or so, whereas hats 1 is more of a regular fizzy hihat at 8khz on every offbeat.
I chucked a Dyneq cut at 14khz on Hats1 with sidechain active, triggered by the 14khz of Hats2. That worked fine, so then I put another Dyneq on Hats2 so the 8khz side frequency content of Hats1 could cut through on every off beat as it hits, but only when it passes through that specific freq range as it rises freq. Activated the sidechain of Dyneq on Hats2, but it would only appear as a send option on anything BUT Hats1. If I remove the original Dyneq or remove the send from Hats2 to Hats1, the sidechain appears as a send option from Hats1 to Hats2. Insert and activate, Cubase hides it again.
I understand the eg I gave is probably clunky and over complicating things (I tend to do this), and I did end up working on arrangement, mixing and just routing the output of either Hat channel to a group to allow the ‘vice-versa’ sidechaining. Still, I would be interested to know why Cubase does this with VST outputs, and if it is as muzicman is wondering and just Cubase ‘playing it safe’? I am struggling to see how sending two channels into the plugin insert sidechains of each other would create a loop. Am I missing something obvious?
Again sorry to revive a dead thread, but after searching on here the OP’s questions in this thread re hiding routing options are precisely what I am curious about, albeit in VST output channels rather than groups and fx.