My primary Mac for Poser is running Sierra, but I do have a MacBook running Catalina that I use with Poser. Poser Pro 11.2 runs well on it, including the built-in library. I do need to get the latest public update to Poser as my build is around 11.2.320, I think. Do note that there are now alpha release builds of Poser Pro specifically for testing with Catalina. I'm not brave enough to try those yet.

Lee