Sadly not all usb-c cables are the same. You mention that this works for your iPad, is your iPad a usbc-connection or are you using a different cable, like a Lightning port to USB-C cable? As LongHiker stated, you may need to get a different USB-C cable for this, one that supports the video standards. This can be difficult to determine, as not all manufacturers are forthcoming with this information. If your monitor came with a USB-C cable, then your best bet would be to use that one as it should support the standard.
