Jittery mouse on LG 4k external monitor

Happy new year everyone!

I recently upgraded both my MBP and external monitor, and I've noticed that with the new configuration, my mouse cursor is much more jittery on the external monitor than it used to on my old (ancient, actually) 23" Apple Cinema Display. I've seen other discussions about this topic, but have been unable to determine a solution from the archived posts.

OLD CONFIGURATION:

• 2014 MBP running Mojave
• Apple 23" Cinema Display
• DVI to ADC adapter plugged into Display port
• Logitech wireless USB mouse plugged into monitor

NEW CONFIGURATION:

• 2018 MBP running Catalina
• LG 27UL600 display
• Ultradrive Kit j5 create USB-C dock, with monitor plugged into HDMI port
• same Logitech wireless mouse from old configuration, but mouse plugged into external USB keyboard, which is also plugged into j5 create adapter

In the new configuration, the cursor is responsive, but just jittery on the LG external display, but smooth as usual on the laptop screen.

I know there are a number of variables that have changed between the old and new system, but it seems like this is a common problem based on old discussions I've been looking at. I did see one YouTube video about changing refresh rate, but I don't see a way to change that on the LG monitor, and the documentation says it's 60Hz.

Thanks!