Side Chains not showing up as sends on certain tracks

I’ve seen countless posts for over a decade about this bug that decides to haunt a specifc project every year or so, but never a solid answer.

The issue is the classic: side chain has been activated on a track’s plug-in (compressor, or in this case trackspacer) & it will only appear in some audio tracks’ send options but not in others. I’ve always managed to cobble together a work around whether it’s creating a new audio track & pasting everything onto it or duplicating the track, but in my currently haunted project nothing is working at all. I’m creating completely new audio tracks & pasting everything onto it & the side chain send is still not showing up as a send option for some tracks, duplicating the track does absolutely nothing anymore. I’ve seen people say that creating a duplicate plug-in or restarting Cubase works but genuinely nothing works for this project anymore.
I’ve raised it as an issue with Steinberg but have had no response. Does anyone know a fix for this bug or can hopefully tell me that I’m doing something obviously wrong that is causing this issue because this bug is honestly the most infuriating, time consuming, & creatively inhibiting thing I’ve ever come across with Cubase.