I have an early 2014 macbook air and per this I can connect it with a 4K monitor with some success.
After resetting the NVRAM (Opt+Cmd+P+R) I got my Display Settings to show ASUS VP28U with mirror option ticked.
However, the monitor does not show anything. Given the fact it detected the display and made my macbook screen super small , is there a workaround ?
As soon as mirror option is unticked, my screen reverts to old display.