Clock uncertainty warnings under 10.0

I'm still not following. If you have derive_clock_uncertainty in your .sdc, everything should be taken care of for you. There's no problem that derive_clock_uncertainty isn't used until the next update_timing_netlist, as those steps should always happen one after another. I think derive_clock_uncertainty should just happen behind the scenes and there would be no reason to add it to your design, but once you know about adding it there shouldn't be any probelms.