Problem calibrating external display

Yes, it did not appear on the BenQ 270C display that I'm trying to calibrate either. I have now discovered that it depends on how the monitor is connected. I was connecting via an HDMI to USB-C adapter. My monitor also supports USB-C and when I use that connection, the HDR checkbox appears. I wonder if this happens with other monitors or whether that is peculiar to the BenQ SW270C?

Have you tried changing the input to USB-C using the controls on the SW270C? Press any of the buttons on the front panel of the monitor to bring up the main menu, then select the input menu and change the input to USB-C. If you've already done this, then try the HDMI cable and change the monitor input accordingly. If you've tried this and had no joy, you may indeed have a faulty USB-C cable. If you end up having the calibration issues I encountered trying to calibrate the monitor, I overcame my issues by clean installing OS Catalina. This is a pretty drastic step but I was able to test it first by clean installing OS Catalina on a bootable external SSD and selecting this drive in recovery mode. Palette Master Elements and my i1Display Pro worked perfectly in this environment which gave me the confidence to then go ahead and clean install the OS on the internal HD. My MacBookPro originally shipped with High Sierra and it seems that the successive upgrades through Mojave and then Catalina leaves legacy artefacts that can cause problems. An added benefit is that Adobe Camera Raw now recognises my Canon 5D MkIV when I connect it to the MacBook which it didn't previously. Good luck and I highly recommend BenQ Ambassador Artisright's YouTube channel for BenQ issues. He helped me a lot.