The API picks the maximum sweep time that ensures all configuration is met. That includes RBW/VBW/sweeptime. Setting a small sweep time ensures the minimum sweep time is chosen based on RBW/VBW.
I would ignore the uncal warning flag for now if it’s being thrown on the first sweep. I suspect it’s being set erroneously. I was able to reproduce this using your settings. The uncal data flag usually indicates network data loss, I’m going to need to investigate further to determine why it’s returning this warning for this configuration.
Andrew