I suddenly also ran into this with v4.1.2. I add the model, have a process, have the model also selected in the process, and when I slice, I get build time 0 hours and there is nothing to see. The slice process is also instantaneous, so it actually is skipping the model.
When I add supports, I can see the paths for the support, but the model itself is not sliced.
It has worked before, but suddenly stopped.
Please help, because also other models cannot be sliced anymore.