Yes, I have this issue all the time where Iris 2 will not bounce automation data properly when bouncing offline in Cubase, either resulting in silence, or simply something "incorrect." I've also experienced this when automating some other Izotope plug-ins–I can't trust that they'll bounce properly.
Maybe this is a Mac thing based on Jaap's comment.
The workaround I have at the moment is to use the VST 2 versions instead of VST3. Try that out, and see if you get the correct result. Of course this can come with other problems, based on what you're trying to achieve.
I reached out to Izotope about this a while ago and they simply told me to bounce in real-time (not a permanent solution IMO), but I've reached out again and am in the middle of a new conversation. I've had this issue for a while, and I actually abandoned Iris because this was a show-stopper. What I would do was create a pre-routed print bus in my template so I could solo Iris and print into the DAW, then batch export that later. Render in Place will also give you a "bad" result.
Will update here if I hear anything interesting from Izotope.
TL;DR: You're not crazy.