When soloing a channel, normally Cubase will also solo the sends for that channel also. I have a track in my session that when I click solo, the FX sends are not also soloed. How did this happen? And is there a way to fix it?
Is the Send activated? Does the signal pass thru the Send? Is it an Audio track or an Instrument track?
To fix it, I would try to remove the Send from the source Audio(?) track and remake the routing to the Send back. Hopefully this should fix it.
I’ve seen such behaviour in long grown projects that were ‘alive’ over different Cubase versions. Sometimes copying the FX track helps ‘refreshing’. Of course it’s necessary to change the send routings to the copy manually then.