Dual monitors, 4K & 1080, laptop

I recently purchased a LG 4K, 144Hz gaming monitor for my gaming PC that I would also like to use as a second monitor for my “work from home” station, which currently consists of a HP Elitebook laptop connected to a Samsung 1080p, 60Hz monitor. I thought that a combination of (1) Using my laptops USB-C/Thunderbolt port (using a 4K@60Hz USB C to HDMI Cable Adapter connected to my 4K monitor), and (2) Using my laptops HDMI port (using a standard high speed HDMI cable connected to my 1080p monitor) would yield me successful dual screen results. However, it does not work. Instead, my 4K monitor loses input signal and shuts down while my 1080p monitor will flash on and off and eventually just a black screen. The issue does not occur if I do one or the other of the two things mentioned above (using just one screen) however persists as soon as I go to plug in a 2nd screen using the other option. I also tried reducing the resolution of my 4K monitor to 1080, no luck. I am thinking it may have to do with the different refresh rates, possibly different resolutions, or possibly I am not using the right cords. P.S., my laptop consists of one HDMI input only, and one USBC port. Any thoughts would be greatly appreciated!