4k monitor, no 4k image

Issue: I cant seem to get a 4k image on my monitor that is connected via HDMI + apple's usb-c av adapter. I only get 3360x1980

Steps taken to troubleshoot:

Update all software.

Verify the HDMI cable and dongle - I connected my 4K TV via the HDMI cable and it outputted 4k@60

Verify the monito r- using a github program, I was successfully able to output a 4k image to my monitor.

Try usb-c - This worked, but my the reason i was using the the dongle was for the usb port

Try different brand of adapter - Only 3360x1980, just like the apple dongle.

Ideas - the 3360x1980 only seems to occur with this monitor. I know this monitor capable of 4k over HDMI since I was able toget 4k, using 3rd party software. Therefore I know this is not a limitation of the monitors hardware and HDMI port. However this was third party software which can potential damage hardware. My usb drive, connected to the dongle, diffidently behaved differently with the third party software. YIKES! To me, this seems like a handshake issue between the two devices, my mac and the monitor. The monitor is a LG 27BL85U. See screen shot for more info.

Any ideas on how to get a 4k image would be greatly appreciated.