HDMI is a universal standard. If your cable is HDMI and the port is HDMI, then they absolutely have to fit together.
If they don’t, either one or the other is not actually HDMI, or there’s a physical issue with either one or both.
Tell us what make and model of multiport hub you have. And provide a picture of the cable, both ends and the port to help us diagnose.
The suggested adapter will avoid using the hub and existing cable, by plugging directly into a usb-c port on the Mac and into the hdmi port of the monitor.
According to ASUS website the monitor has a display port in addition to HDMI, so you may simply be mistaking a display port cable with HDMI.