It’s more that the community is helpful… but no one in the community is still using 8 to help out. No one can check this for you. I don’t recall the limitation you are experiencing, it doesn’t sound right at all. You must have a routing error or the version # you’re using might be one that had a Sidechain bug, the Sidechain button disappearing. I vaguely remember something like that happening many years ago.
8 isn’t just 2 generations old, it’s 4, Cubase do big releases in .5 increments, every year. I strongly support upgrading. If not every year, every other year. You get to save a bit more cash every other year. if you leave it longer you get left behind. When you finally do upgrade, so many new features will go unnoticed, the learning curve is higher, a lot more changes to absorb.