First-Get a professional Waveform Monitor from Leader or Tektronics, I’ve heard people using Veescope Software via a PC to do their color measurements and works.
Second- I would be looking at the Vectorscope and not the Histogram that’s what engineers go off of to measure color and has the correct targets that will tell you if your are exceeding legal levels or not.
Check the settings on your broadcast safe filter, I’m not sure how Vegas operates but there should be some control settings that will allow you change how far to limit your colors and luminance levels.